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Pyrolysis of Prunus dulcis was performed in the presence off our catalysts (ZnCl2, Fe2O3, Alumina, and ZSM-5) using a fixed bed tubular reactor. The factors affecting the product yield were premeditated. Prunus dulcisshowed a high heating value of 19.72 MJ/Kg which makes it very efficient for biofuel usage. Biochar obtained showed high carbon content and large heating values. Different pyrolytic product yields were obtained with different catalysts. Among all the catalysts, alumina and ZSM-5 showed a maximum yield of liquid product. FT-IR, GC-MS, and elemental analysis were performed to determine the product yield and bio oil compositions. [ABSTRACT FROM AUTHOR]

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Oil shale samples from Longkou City, Shandong Province, China, were pyrolyzed in a fixed bed reactor at retorting temperature varied from 400 to 550°C under nitrogen atmosphere with heating rate of 15°C/min. The influence of retorting temperature on the yield and characteristics of shale oil and retorting gases were determined. It was observed that the oil yield increased to the maximum value, 15.68 wt%, as the retorting temperature increased from 440 to 550°C. And increasing retorting temperature improved also gas yields, but reduced the char yield. The contents of H2, CO2, and CH4 in the retorting gas increased with the rising of retorting temperature. The ratio of alkane/alkene hydrocarbon (C1-C5) decreased because of the secondary cracking reactions of gas phase in the high temperature. The carbon and nitrogen contents of shale oil increased with increasing retorting temperature, while those of hydrogen and oxygen decreased. The sulfur content was not significantly affected by the retorting temperature. In addition, the shale oil obtained from 550°C had the lowest aromatic content, 25.12 wt%, and the highest saturate content, 50.03 wt%, compared to the other retorting temperatures due to the cracking of aliphatic compounds. The alkanes with 8-34 carbons and alkenes with 8-27 carbons were detected in the shale oil. The concentration more than 20 mg/goil was C23-C30 in the range of 400-550°C. The total content of n-alkanes decreased to 369.25 mg g-1oil, and that of n-alkene reached the maximum value at 550°C, 181.62 mg/goil, with the rise of retorting temperature. It was demonstrated that the higher temperature was beneficial to promoting the reaction of aromatization, dehydrogenation, fraction, and other reactions in the pyrolysis process. [ABSTRACT FROM AUTHOR]

The analysis of this study focuses on the production of H2 based on the methanol steam reforming in an isothermal, steady state and one-dimensional model. Two reactors namely, fixed bed reactor (FBR) and H2 selective membrane reactor (MR) are being evaluated by simulation. FBR consists of a cylindrical column packed with Cu/ZnO/Al2O3 catalyst particle bed, whereas MR is a cylindrical reactor with one reaction tube consisting of an inert nature membrane (Pd/Ag) are considered. At the complete conversion of methanol, the yield of H2 is significantly affected by H2 selective membrane, temperature and pressure conditions. H2 yield of 2.72 has been achieved after the almost complete conversion of methanol at 593 K temperature, the pressure of 1 atm and steam/methanol ratio of 1.5 in FBR. H2 yield, molar flow rate of CO2 has also been increased, and CO concentration has been reduced by using MR. Similarly, H2 yield has increased to 2.76 with decreasing CO concentration using MR at the same operating conditions with an increase in pressure in the reaction zone to 2 atm. Hence, the results indicate that the H2 yield with a small amount of CO has been achieved in MR at optimum operating conditions. Abbreviations: FBR: Fixed Bed Reactor; MR: Membrane Reactor; SRM: Methanol Steam Reforming; MD: Methanol Decomposition; WGS: Water Gas Shift; PROX: Preferential Oxidation; S/M: Steam to Methanol Molar Ratio in Feed; O/C: Oxygen to Carbon Ratio; L/D: Length to Diameter Ratio; POX: Partial Oxidation; ATR: Auto-Thermal Reforming; SR: Sweep Ratio (sweep gas/methanol molar ratio) [ABSTRACT FROM AUTHOR]

• The effect of temperature on H 2 yield is divided into two control regions. • S/C influences H 2 yield mainly through CCE rather than CO 2 selectivity. • Banana peel gasification has great potential for producing H 2. • Drying treatment contributes to the increase of CO 2 selectivity and CCE. The Gasification performance of banana peel was examined in a fixed bed reactor. Effect of temperature, steam to carbon ratio (S/C), drying treatment on syngas composition, gas yield, CO 2 selectivity and carbon conversion efficiency (CCE) were investigated. The influence of temperature and S/C on hydrogen production was investigated by thermodynamic analysis. The transient characteristics of banana peel steam gasification were investigated by monitoring the evolutionary behavior of syngas production. An increase in S/C can lead to an increase in the selectivity of CO 2 , but excess steam (S/C > 21.7) causes a decrease in H 2 yield and CCE. The increase of temperature is beneficial to the increase of CCE, but which leads to a decrease in CO 2 selectivity. When S/C = 27.1, the effect of temperature on H 2 yield can be divided into CCE control region and CO 2 selectivity control region. At temperature < 1023 K, H 2 yield is more sensitive to the changes of CCE. While at temperature > 1023 K, CO 2 selectivity has a more significant effect on H 2 yield. When S/C = 21.7 and temperature is 1023 K, the yield of H 2 produced from the fresh banana peel gasification reaches the maximum value (76.1 ml/g). [ABSTRACT FROM AUTHOR]

Plasma-assisted catalytic cracking is an attractive method for producing biofuels from vegetable oil. This paper studied the effect of reactor temperature on the performance of plasma-assisted catalytic cracking of palm oil into biofuels. The cracking process was conducted in a Dielectric Barrier Discharge (DBD)-type plasma reactor with the presence of spent RFCC catalyst. The reactor temperature was varied at 400, 450, and 500 ºC. The liquid fuel product was analyzed using a gas chromatography-mass spectrometry (GC-MS) to determine the compositions. Result showed that the presence of plasma and catalytic role can enhance the reactor performance so that the selectivity of the short-chain hydrocarbon produced increases. The selectivity of gasoline, kerosene, and diesel range fuels over the plasma-catalytic reactor were 16.43%, 52.74% and 21.25%, respectively, while the selectivity of gasoline, kerosene and diesel range fuels over a conventional fixed bed reactor was 12.07%, 39.07%, and 45.11%, respectively. The increasing reactor temperature led to enhanced catalytic role of cracking reaction, particularly directing the reaction to the shorter hydrocarbon range. The reactor temperature dependence on the liquid product components distribution over the plasma-catalytic reactor was also studied. The aromatic and oxygenated compounds increased with the reactor temperature. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Interactions between corncob volatiles and lignite was obvious. • A two-stage, three-tube fixed-bed reactor was used in this study. • Significant interactions were observed on liquid and gaseous yields and components. • The reactivity of lignite char was affected by interaction. • Inorganic components showed varied catalytic effect at varied temperature and phase. Abstract The interactions of corncob volatiles and lignite in the process of rapid co-pyrolysis and the effects on their product distributions and properties were examined for the efficient co-utilization of biomass and lignite. A novel two-stage, three-tube reactor was used to do co-pyrolysis experiments, which allowed the verification of interactions occurred only between corncob volatile and lignite. Raw corncob and its demineralized sample were employed for studying the different interactions of organic radical fragments and AAEMs in corncob volatiles on lignite. It was found that the interactions resulted in the decreased liquid yields but increased gas yields, and varied oxidative reactivity of lignite char by changing its chemical structure. There exist different effects on product distribution and property for organic radical fragments and AAEMs in corncob volatiles. The former could promote the interaction of nascent char-volatiles and accelerate the stabilization of radical fragments, the latter mainly catalyzed the decomposition reaction of corncob matrix below 700 °C, while mainly volatilized and catalyzed the reactions between volatiles in gaseous phase when the temperature was above 700 °C. [ABSTRACT FROM AUTHOR]

The performance of catalytic tri-reforming under industrially relevant situations (e.g., pellet catalysts, pressurized reactor) was investigated using surrogate biogas as the feedstock. Tri-reforming using Ni/Mg/Ce0.6Zr0.4O2/Al2O3 pellet catalysts was studied in a bench scale fixed-bed reactor. The feed molar ratio for CH4:CO2:air was fixed as 1.0:0.70:0.95. The effects of temperature (800-860°C), pressure (1-6 bar), and H2O/CH4 molar feed ratio (0.23-0.65) were examined. Pressure has substantial impact on the reaction and transport rates and equilibrium conversions, making it a key variable. At 860°C, CO2 conversion increased from 4 to 61% and H2/CO molar ratio decreased from 2.0 to 1.1 as the pressure changed from 1 to 6 bar. CO2 conversion and H2/CO molar ratio were also influenced by the temperature and H2O/CH4 molar ratio. At 3 bar, CO2 conversion varied between 4 and 43% and the H2/CO molar ratio varied between 1.2 and 1.9 as the temperature changed from 800 to 860°C. At 3 bar and 860°C, CO2 conversion decreased from 35 to 8% and H2/CO molar ratio increased from 1.7 to 2.4 when the H2O/CH4 molar ratio was increased from 0.23 to 0.65. This work demonstrates that the tri-reforming technology is feasible for converting biogas under scaled-up conditions in a fixed-bed reactor. [ABSTRACT FROM AUTHOR]

Layered loading of catalysts with different catalytic properties is studied for oxidative coupling of methane reaction (OCM) in a fixed bed reactor. Layered loading of a more active catalyst Ag-Mn-Na 2 WO 4 /SiO 2 in front of a more selective one Ce-Mn-Na 2 WO 4 /SiO 2 compared to loading Mn-Na 2 WO 4 /SiO 2 catalyst only, lowers reaction temperature and increases selectivity. Such layered loading broadens the temperature range to achieve a high selectivity, which is important for OCM reaction carried out with multi-stage adiabatic fixed bed reactor. Similarly, with a very active La-Ce oxide catalyst loaded in front of a selective catalyst Ce-Mn-Na 2 WO 4 /SiO 2 , the temperature needed to start the reaction is lowered significantly. Therefore, a catalyst bed such as La-Ce oxide can be used as a “pre-heater” for the high temperature OCM reaction to lower the feed temperature. The total CH 4 utilization can be improved with this loading strategy. [ABSTRACT FROM AUTHOR]

Pyrolysis studies on conventional biomass were carried out in fixed bed reactor at different temperatures 300, 350, 400 and 450 °C. Agricultural residues such as corn cob, wheat straw, rice straw and rice husk showed that the optimum temperatures for these residues are 450, 400, 400 and 450 °C respectively. The maximum bio-oil yield in case of corn cob, wheat straw, rice straw and rice husk are 47.3, 36.7, 28.4 and 38.1 wt% respectively. The effects of pyrolysis temperature and biomass type on the yield and composition of pyrolysis products were investigated. All bio-oils contents were mainly composed of oxygenated hydrocarbons. The higher area percentages of phenolic compounds were observed in the corn cob bio-oil than other bio-oils. From FT-IR and 1 H NMR spectra showed a high percentage of aliphatic functional groups for all bio-oils and distribution of products is different due to differences in the composition of agricultural biomass. [ABSTRACT FROM AUTHOR]

In this work multicomponent breakthrough curve experiments of a SMR type off-gas containing hydrogen, carbon monoxide, methane and carbon dioxide on a BPL activated carbon fixed bed have been performed at 3 bar and temperatures ranging between 298 K and 338 K. The experimental results have been compared to predicted breakthrough curves simulated with a mathematical model with high accuracy. Pure component breakthrough curve experiments have been previously performed in order to obtain the adsorption capacities. The Langmuir isotherm model has been used for pure component adsorption and the Extended Langmuir isotherm model for multicomponent adsorption. [ABSTRACT FROM AUTHOR]

Temperature is an important parameter in technical processes because almost all mechanical, electrical, magnetic, and optical properties as well as the selectivity in chemical reactors are temperature-dependent. Fiber-optic measurement technology enables minimally invasive, simultaneous temperature detection at numerous measuring points along a sensor fiber and is used to record temperature and strain profiles. This article discusses its application in heterogeneous gas phase catalysis in fixed-bed reactors. [ABSTRACT FROM AUTHOR]

In this study, a novel method optimizing direct dimethyl ether generation from syngas is proposed. A bi-functional catalyst is used containing commercial catalyst for direct DME synthesis (CuO/ZnO/Al 2 O 3 ). The length of reactor has been discretized into twenty segments and optimum temperature profile in the inlet of each segment and the amount of water removal from the main stream are calculated. This optimization is done via differential evolution (DE) method, in which the inlet temperature and water removal flux in each segment are considered as the decision variables and mole fraction of dimethyl ether in the reactor outlet is the objective function. Three different cases are considered. In the first case, inlet temperature of each segment has been optimized. Then, flux of water removal is considered. And, finally, a combination of two previous cases is investigated. Obtained results of this novel theoretical study showed that water removal results in more methanol production; and Consequently, dimethyl ether production increased. By applying the proposed optimization methods, 1.5%, 55% and 70% enhancement in the dimethyl ether production have been obtained in comparison with the conventional reactor of direct dimethyl ether production. [ABSTRACT FROM AUTHOR]

We present the design and investigation of a novel chemosorption vacuum pump (CSVP) for discharging the exhaust gases of a chemical oxygen-iodine laser system diluted with carbon dioxide (CO-COIL). The CSVP comprises two fixed-bed reactors separately filled with CO/HO and O/I/Cl adsorbents, which can efficiently chemically absorb the CO-COIL exhaust gases at room or higher temperature. We consider the effects of the adsorbents in different specifications and fixed beds of various constructions on the adsorption performance of the CSVP. We develop and study the sealed CO-COIL system with the CSVP. We achieve a stable operation with a cumulative duration time of 40 s for four runs and an average output power up to 2.0 kW at a Cl flow rate of ∼158 mmol/s and a CO flow rate of 132 mmol/s. The experimental results indicate that the COIL system with the CSVP performs similarly to a conventional COIL with a vacuum tank. Taking into account that the CSVP is free of vibration and noise, avoids air pollution, is easily operated, and has a short preparation time, we believe that the chemosorption vacuum pump is an excellent alternative pump system for a transportable COIL system. [ABSTRACT FROM AUTHOR]

Experiments are conducted on a laboratory-scale fixed bed combustor. This article discusses some of the data analysis methodologies that define the onset of steady state conditions, which are widely reported in the literature but poorly defined. The effects of using different methods to determine the onset of the steady state performance, and to correct thermocouple data so as to account for radiative effects, are also presented. Results show that using a combination of CO and NO emissions with free-board temperatures (at multiple axial positions) is more effective than other emissions, using temperatures (only) or the fuel burning rate (kg m–2s–1). An important indicator is to analyze the percentile deviation of temperatures and emissions, compared to only using the time evolution of these variables. To characterize the significance of correcting thermocouple data for radiative (wall) losses, two numerical models (aspirated and bare bead) were compared. Radiative effects on thermocouples were found to be most prominent nearer to the downstream secondary air inlet due to the cooler wall temperature. Due to the likely radiative effects from freeboard deflectors, the sensitivity of these outcomes to the presence of downstream deflectors is also presented. [ABSTRACT FROM PUBLISHER]

The pyrolysis of a Shanghai municipal sewage sludge sample was conducted using a slowly heating and gas sweeping fixed-bed reactor. The pyrolysis liquids produced at three predetermined temperatures (400, 500 and 700 °C) were fully examined using GC × GC-TOFMS. The pyrolysis mechanism of the sewage sludge was analyzed online using in situ FTIR from ambient temperature to 600 °C. The primary objectives of this study are to (i) determine the chemical composition of the pyrolysis liquids, and (ii) to assess the effect of temperature on the composition of the liquid products. Whereas studies that use GC–MS have normally found hundreds of compounds, analysis of the pyrolysis liquids by GC × GC-TOFMS detected thousands of compounds. Moreover, this method detected some isomers as well. Pyrolysis in this pyrolyzer was observed to produce abundant cyclosiloxanes, which were rarely reported in previous studies, and this may be related to the use of a comprehensive analytical method (GC × GC-TOFMS). The temperature dramatically affected the liquid composition. The proportions of monoaromatics and polyaromatic ketones increased with increasing temperature, and theoretically, the high temperature could promote the production of phenyl rings. The generation of long-chain aliphatic amides and nitriles occurred mainly below 400 °C, whereas nitrogen-containing alicyclic hydrocarbons were generated mainly at 500 °C. The cyclosiloxanes were part of the original composition of the sewage sludge and were predominantly released below 400 °C. The variation in the functional group of the sewage sludge was consistent with that of the pyrolysis gas and liquid compositions. [ABSTRACT FROM AUTHOR]

Gasification of dried sewage sludge was performed in a newly developed three-stage gasifier consisting of an auger as well as fluidized and fixed bed reactors to produce a producer gas with low-levels of contaminants. The auger reactor was designed to generate tar in advance, thereby enhancing the tar destruction in the fluidized bed gasifier and fixed-bed reactor. In the study, the effects of each reactor temperature and activated carbon as an impurity absorbent were mainly investigated. The reaction temperatures of the auger and fixed bed reactors were shown to have a strong influence on the tar removal, while that of the fluidized bed reactor mainly affected the producer gas composition. The three-stage gasifier clearly decreased the tar content in producer gas and condensed tar and increased the H 2 production. In an experiment performed with activated carbon at the auger reactor temperature of ∼710 °C and the fluidized bed and fixed bed reactor temperatures of ∼830 °C, the tar and H 2 contents in producer gas were only 22 mg/Nm 3 and ∼29 vol%, respectively. Activated carbon clearly reduced the NH 3 and H 2 S contents in producer gas. The minimum NH 3 and H 2 S contents were 324 and 346 ppmv, respectively. [ABSTRACT FROM AUTHOR]

Fixed-bed reactor is one of the most common reactor types applied in ethanol steam reforming (ESR). Despite the low price, easy application and simple structure, low efficiency is considered as one of the most important challenges for these reactors. Using micro scale structure reactors, new and optimized catalysts, and also micro channels with various arrangements, are some of various procedures that have been used to solve this problem. In this work, for the first time, using ESR, the effect of changing reactor diameter in the longitudinal direction of reactor on the performance of fixed-bed microreactor has been studied. In this way, three reactors A, B and C with conical, cylindrical and inversed conical geometry with equal volumes have been used. The effect of temperature, contact time and S/E ratio on ethanol conversion and productivity of H 2 and CO 2 have been studied. According to the results, conical reactor has the best performance between mentioned reactors. [ABSTRACT FROM AUTHOR]

Torrefaction of pine wood was performed in a tube furnace at three temperatures (220, 250, and 280 °C) for 30 min. Then catalytic pyrolysis of raw and torrefied pine wood was performed using HZSM-5 catalyst in a fixed-bed pyrolysis reactor at 550 °C for 15 min. Torrefaction pretreatment and catalytic pyrolysis have an very important effect on the yield, property, and energy distribution of pyrolysis products. The results showed that the yield of biochar rapidly increased, while that of bio-oil decreased with increasing torrefaction temperature. The oxy-compound content of bio-oil, such as acids and aldehydes, sharply decreased. However, the aromatic hydrocarbon content not only increased but also further promoted by HZSM-5 catalyst. With highest mass yields and energy yields, biochar was also the very important product of pyrolysis. The oxygen content in biomass was mainly removed in the form of CO 2 and H 2 O, leading to increasing CO 2 content in non-condensable gas. [ABSTRACT FROM AUTHOR]

The pinewood was pyrolyzed in the first reactor at a heating rate of 10 °C min −1 from room temperature to 700 °C, and the vapor was allowed to be cracked through the second reactor in a temperature range of 450–750 °C without and with HZSM-5. Attempts were made to determine a wide spectrum of gaseous and liquid products, as well as the mass and element partitions to gas, water, bio-oil, coke and char. HZSM-5 showed a preferential deoxygenation effect via the facilitated decarbonylation and decarboxylation with the inhibited dehydration at 550–600 °C. This catalyst also displayed a high selectivity for the formations of aromatic hydrocarbons and olefins by the promoted hydrogen transfer to these products at 550–600 °C. The bio-oil produced with HZSM-5 at 500–600 °C had the yields of 14.5–16.8%, the high heat values of 39.1–42.4 MJ kg −1 , and the energy recoveries of 33–35% (all dry biomass basis). [ABSTRACT FROM AUTHOR]

Much attention has been given to the valuable products from the pyrolysis of sewage sludge. In this study, the pyrolysis of sewage sludge, biomass (wheat straw) and their mixtures in different proportions were carried out in a thermogravimetric analyzer (TGA) and fixed-bed reactor. The effects of pyrolysis temperature and percentage of wheat straw in wheat straw–sewage sludge mixtures on product distributions in terms of gas, liquid and char and the gas composition were investigated. Results indicate that there is a significantly synergetic effect during the co-pyrolysis processes of sewage sludge and wheat straw, accelerating the pyrolysis reactions. The synergetic effect resulted in an increase in gas and liquid yields but a decrease in char yield. The gas composition and the synergetic effect degree are strongly affected by the wheat straw proportions, and the strongest synergetic effect of sewage sludge and wheat straw co-pyrolysis appears at the biomass proportion of 60 wt.%. With an increase of temperature, the gas yield from the pyrolysis of sewage sludge increased but the liquid and char yields decreased. Moreover, the required heat of co-pyrolysis is significantly reduced compared with the pyrolysis of sewage sludge and wheat straw pyrolysis alone, because of the exothermic reactions between the ash components in two fuel samples. [ABSTRACT FROM AUTHOR]

Experiments were conducted in a bench-scale fixed bed reactor with α-Fe 2 O 3 and γ-Fe 2 O 3 samples to investigate the mechanism of Hg 0 oxidation in the presence of HCl at 80–680 °C respectively. HCl is one of the main impurities in coal-derived fuel gas and its contribution to Hg 0 removal is complex and necessary to research. The experimental results showed that the Hg 0 removal mechanism with HCl could probably be divided into three stages based on the reaction temperature. At low temperature, the Eley–Rideal mechanism with HCl pre-adsorption was the most probable Hg 0 oxidation pathway. As the temperature increased more than 280 °C, Hg 0 removal efficiency differs significantly on α-Fe 2 O 3 and γ-Fe 2 O 3 , and the most suitable mechanism was Langmuir–Hinshelwood. With the increasing temperature to 680 °C, the homogeneous reaction between HCl and Hg 0 as well as Langmuir–Hinshelwood are responsible for the transformation of Hg 0 . We also discovered that the reaction time played a significant impact on the Hg 0 removal at low temperature, and caused the secondary mercury removal efficiency owing to the probable product of FeCl 3 . Additionally, HBr was adopted to compare with HCl, which obviously enhanced the Hg 0 oxidation on α-Fe 2 O 3 . [ABSTRACT FROM AUTHOR]

The pyrolysis oil was produced from the areca tree, available in Assam (India), using a fixed bed reactor along with the investigation of some physical properties such as calorific value, density, viscosity, water content, oxygen content, flash point, fire point, pH value etc. The effect of temperature on pyrolysis products, i.e., liquid and char was analysed and variations of viscosity and density of the bio-oil at five different temperatures were investigated. The maximum kinematic viscosity and density were found to be 12.15 cSt and 1009.3 kg/m3 , respectively. The particle size of biomass sample used was around 2-2.8 mm. Before pyrolysis, proximate and ultimate analyses of the feedstock were performed and the calorific value of the biomass was found to be 13.2 MJ/kg, whereas the calorific value of the pyrolysis oil was found to be 15.2 MJ/ kg. The chemical composition of the oil sample was also investigated with the help of Gas Chromatography & Mass Spectroscopy (GC-MS) and Fourier Transform Infrared (FTIR) spectroscopy techniques. [ABSTRACT FROM AUTHOR]

The migration behavior of the alkali metals and chlorine were studied during rice straw and corn straw gasification in a fixed bed reactor at various temperatures using thermodynamic equilibrium calculations, X-ray diffraction (XRD), and scanning electron microscopy/energy dispersive spectrometry (SEM-EDS). The results showed that K and Na were released mostly in chloride form. The release of potassium, sodium, and chlorine increased upon the increase in temperature from 600 to 1000 °C. The maximum amounts of potassium, sodium, and chlorine that were released from rice straw were 38.9%, 18.7%, and 34.9%, respectively. The maximum amounts of potassium and chlorine that were released from corn straw were 24% and 43.6%, respectively, which occurred at 1000 °C. The maximum amount of sodium released from corn straw was 77.6%, at 700 °C, and the amount of sodium released was greater than that of potassium. Most of the potassium and sodium was converted into insoluble carbonate, sulfate, silicate, and aluminosilicate compounds in the gasification ash. [ABSTRACT FROM AUTHOR]

A method is developed to couple microkinetics with fluid flow in a fixed bed and transport inside the catalyst particles using computational fluid dynamics. Initially, the microkinetics model is solved for a wide range of different temperatures, and partial pressures. Next, reaction rates are mapped into quadratic multivariate splines. Splines coefficients are then imported into our user-defined function, and consequently the reaction rates are evaluated at each iteration simultaneously with the CFD simulations. This method has been applied to our solid particle model to investigate the effects of fluid flow, transport and elementary reaction steps on each other for ethylene and methanol partial oxidations. Reaction rates of all elementary steps as well as species surfaces sites and compositions are evaluated inside the particle. The suggested method can couple complex reaction mechanisms with detailed CFD simulations without increasing the computational time compared with global kinetics methods. [ABSTRACT FROM AUTHOR]

Heat transfer experiments on Longkou oil shale were carried out in a fixed-bed reactor. Temperatures at different positions in the reactor were determined. With increasing heating rate, the temperature difference between center and exterior of the reactor increased, the time needed to get to constant temperature decreased, while the time needed to reach final pyrolysis temperature decreased. A pseudo-homogeneous one-dimensional heat transfer model was developed, and analytical expressions were obtained on the basis of mathematical derivation. It was found that the coefficient of heat conductivity is a polynomial function of temperature. The Longkou oil shale could be seen as a poor heat conductor because of its low coefficient of heat conductivity. Usually, there are many factors to affect coefficient of heat conductivity, including the composition, density, moisture content, temperature, particle size and particle size distribution. Reasonable values of heat conductivity in different temperature ranges were determined using the developed model. The calculated results using heat transfer model for Longkou oil shale are reasonably agreed with actually measured temperature. [ABSTRACT FROM AUTHOR]

This work presents the effect of the simulated sizes of Municipal Solid Waste (MSW) on the combustion process in a fixed bed experimentally and numerically. The effect of temperature, gas emissions, flame front velocity and process rate are discussed for three different sizes of MSW: 10, 30, and 50 mm. The study found that for the operating conditions of the current model, when the diameter of particles is decreased, the bulk density of the material is increased, resulting in a decrease of convective heat transfer as well as combustion speed. As the diameter size of the material particles increase, the height of the post-combustion zone is increased, while the temperature in a high temperature area is decreased, due to the decrease in the material’s bulk density and the excessive increase in porosity. Results also show that the average emission concentration of CO and CO 2 decreases gradually with an increase in the particle diameter size. [ABSTRACT FROM AUTHOR]

The crushing strength and reactivity of carbon-containing iron-ore composites prepared from cold-bonded-pellet derived from steel-making dust (DP) and coke oven gas tar, is examined with a flow-type fixed-bed quartz-made reactor and with a tensile- and compression-testing machine, respectively. When an as-received DP is heated via temperature-programmed heat treatment in He, the intensity of pore-size-distribution peak at 2 nm, specific surface area (S BET ) and pore volume (V BJH ) in the as-received DP tend to decrease with increasing temperature, and the latter two values in the sample, when heated up to 500 (DP/500) and 900 °C (DP/900) become 20 and 5 m 2 /g and 0.06 and 0.01 cm 3 /g, respectively. The peak of the pore size distribution profile around 2 nm completely disappears for the composites prepared from the DP, DP/500 and DP/900, and the S BET and V BJH values in all the composites are < 1 m 2 /g and < 0.01 cm 3 /g, respectively. The crushing strengths of the composites are greater than those of the original samples, measure before the preparation of the composites. The order of the crushing strengths of the composites is similar to that of their V BJH values. When the composites are heated in He, the evolution of CO, CO 2 and H 2 O start around 400 and 500 °C, respectively, and these formation profiles indicate a large peak at about 800–900 °C. The extent of reduction of all the composites at 1000 °C is 85–95%, and the reduction rate for each composite is greater than that of its original sample. [ABSTRACT FROM AUTHOR]

Sodium Dodecyl Sulfate (SDS) is used as a kinetic promoter in gas hydrate formation. In this work, the performance of SDS for carbon dioxide gas hydrate formation in two different fixed bed media: silica sand and zeolite (5A and 13X) has been evaluated. The concentration of SDS was fixed at 0.5 wt%. The experiments were carried out in batch mode with the initial pressure fixed at 3.0 MPa, and the temperature kept constant at 274.65 K. The results showed that hydrate of carbon dioxide with fixed bed of silica sand was significantly promoted by the addition of SDS as compared to the other fixed bed medium used in this study: zeolite 13X. [ABSTRACT FROM AUTHOR]

This study presents a report on pyrolysis of Napier grass stem in a fixed bed reactor. The effects of nitrogen flow (20 to 60 mL/min), and reaction temperature (450 to 650 °C) were investigated. Increasing the nitrogen flow from 20 to 30 mL/min increased the bio-oil yield and decreased both bio-char and non-condensable gas. 30 mL/min nitrogen flow resulted in optimum bio-oil yield and was used in the subsequent experiments. Reaction temperatures between 450 and 600 °C increased the bio-oil yield, with maximum yield of 32.26 wt% at 600 oC and a decrease in the corresponding bio-char and non-condensable gas. At 650 °C, reductions in the bio-oil and bio-char yields were recorded while the non-condensable gas increased. Water content of the bio-oil decreased with increasing reaction temperature, while density and viscosity increased. The observed pH and higher heating values were between 2.43 to 2.97, and 25.25 to 28.88 MJ/kg, respectively. GC-MS analysis revealed that the oil was made up of highly oxygenated compounds and requires upgrading. The bio-char and non-condensable gas were characterized, and the effect of reaction temperature on the properties was evaluated. Napier grass represents a good source of renewable energy when all pyrolysis products are efficiently utilized. [ABSTRACT FROM AUTHOR]

The pathway and kinetics of C 3 –C 7 olefin transformation reactions were investigated in a fixed-bed reactor over a high-silicon HZSM-5 catalyst at 400–490 °C in this work. The main reaction pathway was identified on the observations of the product distribution when the individual olefin was fed alone. The results show that C 7 = proceeds dominantly through a monomolecular cracking, whereas C 4 = and C 3 = through a bi- and trimolecular cracking, respectively, and both mono- and bimolecular cracking for C 5 = and C 6 = . On the basis of the proposed reaction pathway, the kinetic model was developed for each olefin, with the corresponding parameters correlated using the experimental data. Despite the fact that olefin cracking proceeds by a rather complex pathway, a fairly satisfactory agreement between the calculated and experimental data was achieved over the test temperature range of 400–490 °C, and a phenomenon of the minus observed activation energy for both bi- and trimolecular cracking can be well interpreted by the combination of the reaction and adsorption steps on the catalyst surface. [ABSTRACT FROM AUTHOR]

Very little attention has been dedicated to the carrier re-oxidation in chemical looping systems. The work presented in this paper is for the re-oxidation of partially reduced hematite from a cyclic chemical looping fixed bed process. The underlying purpose of this work is to develop engineering rates and mechanisms for the re-oxidation of partially reduced hematite that can be included in CFD models for a chemical looping process. To this end, experiments were run using nominally 1000 g of hematite material in a fixed bed reactor cycling between reduction and re-oxidation. The cyclic processing began with the reduction step then proceeded to the oxidation step repeating this analysis for several cycles ranging from 5 to 10. The re-oxidation process was conducted at temperatures ranging from 745 °C to 825 °C and oxygen concentrations ranging between 9% and 11%. The reduction was carried out at the same temperature as the re-oxidation step at various CH 4 concentrations from 5% to 9%. In this paper, cyclic induced variations in performance are presented as well as the kinetic parameters for the first cycle. The re-oxidation of the depleted hematite occurs through a 2 step parallel process in which oxygen reacts to fill the surface of each grain within the particles and then migrates through oxygen vacancy diffusion to the depleted cores of each grain. [ABSTRACT FROM AUTHOR]

Pyrolysis of Nannochloropsis was carried out in a fixed-bed reactor with newly prepared ceria based catalysts. The effects of pyrolysis parameters such as temperature and catalysts on product yields were investigated. The amount of bio-char, bio-oil and gas products, as well as the compositions of the resulting bio-oils was determined. The results showed that both temperature and catalyst had significant effects on conversion of Nannochloropsis into solid, liquid and gas products. The highest bio-oil yield (23.28 wt%) and deoxygenation effect was obtained in the presence of Ni–Ce/Al 2 O 3 as catalyst at 500 °C. Ni–Ce/Al 2 O 3 was able to retain 59% of the alga starting energy in the bio-oil, compared to only 41% in absence of catalyst. Lower content of acids and oxygen in the bio-oil, higher aliphatics (62%), combined with HHV show promise for production of high-quality bio-oil from Nannochloropsis via Ni–Ce/Al 2 O 3 catalytic pyrolysis. [ABSTRACT FROM AUTHOR]

In the present study, the hydrogasification of chars produced from different rank coals was carried out in temperature up to 1123 K and in the pressure of 5 MPa using a high pressure fixed bed reactor. The experimental results show that the char hydrogasification process can be divided into two stages: an initial stage with sharp decline in hydrogasification rate and a stable stage with slower decline one. To further explore the hydrogasification mechanism, Raman spectroscopy was used to investigate the evolution of the char structure during hydrogasification. The initial stage can be attributed to the rapid reaction of hydrogen and the functional groups, amorphous carbon remaining in char. The stable stage owes to the gradual consumption of amorphous carbon and the ordering of the microstructure, which was indicated by the decrease in I D3 / I G and the increase in I G / I ALL with the increasing carbon conversion. Good linear correlations were found between the hydrogasification reactivity and the band area ratios of ( I D3 + I D4 )/ I G and I D1 / I G , which denote the active sites and the degree of graphitization of chars, respectively. [ABSTRACT FROM AUTHOR]

The kinetic of carbon monoxide hydrogenation over the SiO 2 supported nano-structured Fe–Co–Ce catalyst was studied in a fixed-bed reactor under the conditions as follows: temperature of 523.15–603.15 K, pressure of 2–10 bar, H 2 /CO feed ratio of 1:1 and gas hourly space velocity of 4500 h −1 . Characterization of both precursor and calcined catalysts was carried out using Scanning Electron Microscopy (SEM) and Brunauer–Emmett–Teller (BET) specific surface area measurements. 35 rate equations for CO consumption were derived based on various mechanisms, Langmuir-Hinshelwood-Houngen-Watson (LHHW) and the Eley–Rideal type rate equation. The discrimination of the kinetic models and parameters estimation were carried out by using kinetic data measured in this study. Finally, the best fitted model (FT-XI) was derived from Eley–Rideal kinetics model. In this model rate determining step is formation of CH 2 monomer and the activation energy was obtained 41.14 kJ/mol. [ABSTRACT FROM AUTHOR]

An Indonesian lignite was oxidized using a dual fixed-bed quartz reactor to examine the effect of moisture content, particle size and gas flow rate on low-temperature oxidation characteristics. The self-heating characteristics of dried samples have been further systematically investigated. During oxidation experiments, the temperature profiles of coal were recorded and CO 2 and CO gases were analyzed using gas chromatography. The temperature of coal samples in air increased monotonically, successively exceeding the separation point temperature (SPT) and the crossing point temperature (CPT). SPT, the initial point of self-heating during oxidation, significantly depends upon water content of coal and its removal during drying. It was found from the SPT values that oxidation rate of lignite was highest at moisture content between 6% and 13%. The CO 2 and CO production rates during the self-heating process increased with decreasing particle size, but these effects decreased gradually with increasing drying intensity due to “pore collapse” of lignite during drying. Both SPT and CPT for each dried samples decreased with decreasing particle size, indicating a more rapid self-heating at smaller particle size. The progressive decrease in dependence of the CO 2 and CO production rates on gas flow rate with increasing drying intensity indicated that drying causes the transition of oxidation reactivity controlled by bulk diffusion to that by oxidation kinetics, which altered the net effect of heat loss and supply of oxygen in response to increasing gas flow rate, even resulting in change of the critical moisture range at high gas flow. [ABSTRACT FROM AUTHOR]

In this study, pyrolysis of hornbeam ( Carpinus betulus L.) shell residues was investigated to determine the optimum pyrolysis conditions and the physical and chemical characteristics of bio-oil and bio-char. Experiments were performed at the pyrolysis temperatures of 400, 450, 500, 550 and 600 °C, heating rates of 7, 15, 30 and 50 °C min −1 and nitrogen flow rates of 50, 100 and 150 cm 3 min −1 . The highest bio-oil and bio-char yields were 24.67% and 40.30%, respectively. The thermal degradation of raw material was studied in inert atmosphere by thermogravimetric (TG) and derivative thermogravimetric (DTG) analyses. The elemental composition, higher heating value, density and viscosity of the bio-oil was determined, and then the characterization of the bio-oil was performed using various chromatographic and spectroscopic techniques. Higher heating value, fixed carbon, ash and carbon contents of bio-char were determined. Moreover, the scanning electron microscopy (SEM) images, Fourier Transform Infrared Spectroscopy (FTIR) and Brunauer–Emmett–Teller (BET) analysis of the bio-char were further analyzed. The experimental results showed that the obtained bio-oil can be used as liquid fuels and the bio-char could be used for the production of activated carbon. [ABSTRACT FROM AUTHOR]

The hydrogasification of a low-rank coal was carried out in a two-stage fixed bed reactor with a focus on the separate effects of hydrocracking temperature, hydrogen pressure and vapor residence time on the formations of gaseous and liquid products, particularly the oxygen-containing products. While the yields of CH 4 increased with the increase of hydrocracking temperature (500–750 °C) and hydrogen pressure (0.1–5.0 MPa), the yields of CO 2 showed a downtrend. Both the yield of CH 4 and that of CO 2 changed insignificantly with the vapor residence time (20–100 s). The yield of CO varied somewhat complicatedly with the hydrocracking conditions. The gas generation was influenced not only by the hydrocracking of volatile matter but also by the gas-phase reactions. The increased severity of hydrocracking substantially enhanced the yield of BTX (benzene, toluene and xylene), even with the strengthened decomposition of toluene and xylene. Phenol was hydrocracked to an increased extent, with increasing hydrocracking temperature and hydrogen pressure, whereas naphthalene was barely hydrocracked till the hydrogen pressure was elevated to 5.0 MPa. The pressurized hydrogen intensified the hydrogenation of oxygen atoms in coal forming more water. The yields of water arising from the hydrogenation reactions were found to have a good correlation with the oxygen contents in various coal and biomass samples. [ABSTRACT FROM AUTHOR]

In this paper, a dynamic model is proposed for the charging process of a cold energy storage made of a fixed bed of spherical nodules containing a Phase Change Material (PCM). During the charging process, even if the temperature of the cooling liquid that flows through the storage is uniform, the solidification process does not begin at the same temperature among the nodules due to the supercooling phenomenon. A first number distribution can be defined according to the solid mass fraction among the nodules experiencing solidification. At the end of the solidification process, the temperature of the solid phase is not the same among the nodules population having completed the solidification. A second number distribution can be defined according to their mean temperature. In order to calculate the time evolution of these two number distributions, we propose to use the population balance equation approach coupled with nodules energy balance equations. The resulting partial differential equations are spatially discretized by the finite difference method. The supercooling phenomenon is taken into account as a boundary condition of the population balance equation associated with the solid mass fraction by using a nucleation kinetic model. The resulting set of ordinary differential equations is numerically solved. The model is applied for simulating the charge cycle of an ice storage system. Good agreement between simulation results and experimental data is achieved. [ABSTRACT FROM AUTHOR]

The Conjugate Gradient Method (CGM) is adopted in this study to estimate simultaneously the unknown conversion and temperature-dependent reaction rates for a fixed-bed reactor by using interior measurements of conversion and temperature distributions. The validity and accuracy of this inverse fixed-bed reactor problem was examined using the simulated exact and inexact conversion and temperature measurements in the numerical experiments. Numerical simulations indicate that the estimation of the conversion and temperature-dependent reaction rates can be obtained quickly on an Intel Xeon Core 2 2.00 GHz personal computer and the estimations are still reliable when measurement errors are included since in test case 1 the maximum average errors for the estimated R 1 ( r , z ) and R 2 ( r , z ) are obtained as 0.85%, and 1.4%, respectively, in test case 2 they are 2.58% and 3.98%, respectively. [ABSTRACT FROM AUTHOR]

In the present study, pyrolysis of Mesua ferrea seed cover (MFSC) and Pongamia glabra seed cover (PGSC) was performed to investigate the characteristics of bio-oil and its sub fractions. In a fixed bed reactor, the effect of temperature (range of 350–650 °C) on product yield and quality of solid product were monitored. The maximum bio-oil yield of 28.5 wt.% and 29.6 wt.% for PGSC and MFSC respectively was obtained at 550 °C at heating rate of 40 °C/min. The chemical composition of bio-oil and its sub fractions were investigated using FTIR and 1 H NMR. GC–MS was performed for both PGSC and MFSC bio-oils and their corresponding n-hexane fractions. The results showed that bio-oil from the feedstocks and its sub-fractions might be a potential source of renewable fuel and value added chemicals. [ABSTRACT FROM AUTHOR]

In this study, experimental works for a Turkish lignite in a fixed bed dryer were carried out. Drying experiments were carried out at 70, 100 and 130 °C drying air temperatures, 0.4, 1.7 and 1.1 m/s drying air velocities, 80, 130 and 150 mm sample heights and 20, 35 and 50 mm sample sizes. Suitability of twelve thin-layer drying models in describing the drying kinetics of lignite was evaluated by using statistical analyses. The results show that Wang&Singh model is the best model describing the drying behavior of coarse lignite particles in a fixed bed dryer, which is different from the literature. Additionally, the effects of drying parameters on model coefficients were studied by multiple regression analysis. Finally, apparent diffusion coefficient range was presented. [ABSTRACT FROM AUTHOR]

A CaO-based synthetic sorbent and a NiO/NiAl 2 O 4 catalyst are synthesized and tested under Sorption Enhanced Reforming (SER) conditions in a fixed bed reactor. The effect of temperature, steam-to-methane ratio ( S / C ) and sorbent-to-catalyst proportion ( Z ) are studied. A SER based plant simulation model is implemented to evaluate if the operating conditions chosen allow for a self-sustained plant from a thermal energy consumption standpoint. The most appropriate temperature for SER test is 650 °C. At 600 °C the catalyst seems to be not sufficiently active, while at 700 °C, a longer breakthrough period results. SER equilibrium is reached even at the lowest S / C ratio of 1.6, obtaining H 2 purity of 82 vol.% (dry basis). For the SER based plant simulation developed, the low S / C ratio of 1.6 allows a self-sustained plant where the energy required in the calciner for CaCO 3 decomposition is supplied by burning the off-gas from the H 2 purification unit. [ABSTRACT FROM AUTHOR]

The reduction of NO by reburning using three biomass samples (rice husk, sawdust and corncob) was investigated in a horizontal fixed-bed quartz reactor. The temperatures were ranging from 800 to 1200 °C. The influence of the oxygen concentration entering the reburning zone, the particle size of the biomass and the initial NO concentration on the NO reduction efficiency were studied experimentally. In order to improve the understanding of the relative contribution of each of the pyrolysis gases on the NO reduction, the CO, H 2 , hydrocarbons (mainly CH 4 ), HCN, and NH 3 concentrations in the outlet gas from the reburning zone were measured at combustion temperatures of 800–1200 °C. The experimental results indicated that the biomass type had a significant influence on the NO reduction efficiency. The maximum NO reduction efficiency of sawdust reburning (55 ± 2.4%) was much higher than those of rice husk reburning (43 ± 1.8%) and corncob reburning (44 ± 2.1%). For reburning with sawdust, a highly efficient NO reduction was achieved at oxygen inlet concentrations of 0–1 vol%, particle sizes of 160–370 μm and initial NO concentration of 800 ppmv. For the present operating conditions, the difference in NO reduction for the three biomass samples could be ascribed to differences in the yield of pyrolysis gases through the homogeneous reactions. Hydrocarbons (mainly CH 4 ) were the key species for reducing the emissions of NO, whereas CO and H 2 had little effect on NO reduction. The sum of the HCN and NH 3 concentrations could reflect the tendency for the conversion of the NO entering the reburning zone into N 2 . [ABSTRACT FROM AUTHOR]

A multiscale numerical model based on nonequilibrium thermal effect for melting of metal powder bed subjected to constant heat flux is developed. The volume shrinkage due to density change is taken into account. The nonequilibrium model is discretized by an implicit finite difference method and solved numerically using an iterative tri-diagonal matrix algorithm. The evolutions of powder bed surface temperature and various interfacial locations as well as the melting temperature range during the melting process are investigated. The results show that liquid region, upper and lower parts of mushy zone are formed on the top of unsintered zone as the melting progresses. The duration of the preheating stage shortens and the melting rate accelerates as the initial porosity or initial temperature increases while particle size has much less effect on the melting process. The parametric study shows the melting temperature range of the powder bed widens with increasing initial porosity, decreasing initial temperature or increasing particle size. [ABSTRACT FROM AUTHOR]

The aim of this work is to investigate the contribution of the binder (NiAl 2 O 4 ) on the performances of the oxygen carrier NiO/NiAl 2 O 4 . To this purpose, oxidation/reduction cycles have been performed in a fixed bed reactor using CO as a fuel. The results reveal that the binder can react with the fuel to form CO 2 , and that its total reduction capacity increases with temperature. XRD characterizations performed on the binder (on the fresh and after several cycles) show a shift of the diffraction peaks of NiAl 2 O 4 toward the ones of γ-alumina, which can be attributed to a progressive decomposition of NiAl 2 O 4 to alumina and NiO. [ABSTRACT FROM AUTHOR]

The hydrodenitrogenation (HDN) performance of a Chinese coker gas oil (CGO) was tested in a micro-fixed bed reactor over a nickel–tungsten supported on citric-treated Y zeolite mixed with a titania–silica composite catalyst (NiW/CYCTS) within the temperature range of 360–420 °C, operating pressure range of 5.0–8.0 MPa, liquid hour space velocity (LHSV) range of 0.5–2 h − 1 , H 2 /CGO ratio range of 400–1200 (v/v), and H 2 S concentration range of 1–5 wt.%. The effects of these parameters on the relative conversions of total nitrogen (TN), basic nitrogen (BN), and non-basic nitrogen (NBN) compounds were determined. The conversion of TN compounds enhanced as the temperature and operating pressure increased and as LHSV decreased. BN compounds were easier to be removed than NBN compounds; they were also affected more significantly by the reaction conditions. With increasing H 2 /CGO ratio, the conversion of BN and NBN compounds initially increased and then decreased thereafter. This finding may be attributed to the addition of phenyl-sulfide (PHS) in the feedstock. The kinetic study of the HDN reaction showed that TN, BN, and NBN compounds accorded with the pseudo-first-order kinetic model. The calculation of the rate constants and activation energies indicated that the HDN of NBN compounds controlled the removal of TN compounds. Moreover, the hydrogenation of N-heterocyclic was the controlling step for the conversion of NBN compounds. The results above can guide the development of CGO hydrotreating catalyst. With the information from this paper, the development of CGO hydrotreating catalyst can adjust the properties of the catalyst by decided technology which will favor the removal of NBN containing compounds. [ABSTRACT FROM AUTHOR]

The kinetics of heterogeneously catalyzedself-condensation ofcyclohexanone using Amberlyst 15 as a catalyst has been determinedfrom data obtained in a batch reactor. Temperature and catalyst concentrationranges used were 70–110 °C and 6–66 gcat dry·kg–1, respectively. Runs were carried atboth 5 bar of pressure, in order to avoid the evaporation of the waterproduced, and under vacuum conditions (0.4 bar) in order to removethe water produced. A negative impact of water on the reaction ratewas found due to adsorption onto the catalyst surface and promotionof the reverse reaction. The main products of cyclohexanone self-condensationwere dimers 2-(1-cyclohexenyl)cyclohexanone (D2) and 2-cyclohexylidenecyclohexanone(D3), this reaction being the first step in obtaining 2-phenylphenol.Undesired trimers were obtained significantly at the highest temperatureused. Kinetic modeling was carried out, taking into account reactantand product concentrations (cyclohexanone, dimers, trimers, and water),catalyst concentration, and temperature. Both potential rate law andmodels based on Langmuir–Hinshelwood theory were tested. TheLangmuir isotherm for water adsorption was also determined from experimentaldata. Strong water adsorption was found if water was not distillatedwhile cyclohexanone adsorption was negligible and condensation productswere weakly adsorbed onto the catalyst surface. Adsorption constantscalculated for water and dimers were 0.017 and 3.63 × 10–4kg·mmol–1, respectively. Theactivation energy obtained for trimer production (220.52 kJ·mol–1) was higher than that corresponding to the dimerformation (68.46 kJ·mol–1) explaining the decreasein dimers at the higher temperature. The stability of the catalystwas analyzed in a continuous fixed bed reactor (FBR), finding thatno deactivation took place in the 300 h used as time on stream. Thekinetic model obtained in batch mode was also able to explain thedata obtained in the FBR satisfactorily. [ABSTRACT FROM AUTHOR]