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Bio-glycerol Steam reforming over green and economical Co/sepiolite (SEP) catalysts was a promising strategy to hydrogen production. The activation pretreatment of SEP played a vital role for boosting catalytic behavior of Co/SEP. This work originally explored a full activation of SEP by molten NaOH for tailoring the physicochemical properties of Co-based catalysts prepared by urea precipitation method. Differing from the acid pickling/calcination and molten NaNO3 activation, the molten NaOH treatment enhanced surface area of SEP by desilicication/dealumination effect and further improved the exposure of framework Si and its surface ‘reactivity’. According to the characterization results of N2 adsorption-desorption, XRD, TEM, H2-TPR, CO/CO2-TPD and XPS, it was found that the feathered Co-phyllosilicate formed on Co/SEP-NaOH catalyst, which enhanced the metal-support interaction, surface area and basic/metallic sites. In contrast, the molten NaNO3 treatment facilitated the transformation of SEP into loughlinite and it was adverse to metal dispersion. Therefore, Co/SEP-NaOH catalyst possessed the highest conversion (92%) and H2 yield (68%) during the activity test at 600 °C and the superior resistance to amorphous coke. Additionally, DFT analysis was introduced to simulate the process of glycerol adsorption and decomposition and demonstrated the Co–CoO interface as the primary reaction sites for the catalytic process.

Given the continuing issues of environment and energy, methane dry reforming for syngas production have sparked interest among researchers, but struggled with the process immaturity owing to catalyst deactivation. This review summarizes the recent advances in the development of efficient and stable catalysts with strong resistance to coking and metal sintering, including the application of novel materials, the assessment of advanced characterizations and the compatibility to improved reaction system. One feasible option is the crystalline oxide catalysts (perovskite, pyrochlore, spinel and LDHs), which feature a fine metal dispersion and surface confinement effect via a metal exsolution strategy and exhibit superior reactivity and stability. Some new materials (h-BN, clays and MOFs) also extend the option because of their unique morphology and microstructure. It also is elaborated that progresses were achieved in advanced characterizations application, leading to success in the establishment of reaction mechanisms and attributions to the formed robust catalysts. In addition, the perspective described the upgrade of reaction system to a higher reaction efficiency and milder reaction conditions. The combination of efficient reaction systems and robust catalysts paves a way for a scaling-up application of the process.

Graphene oxide (GO) membranes have received considerable attention owing to their outstanding water-permeation properties; however, the effect of the membrane’s microstructures (such as the distribution of oxidized and pristine regions) on the transport mechanism remains unclear. In this study, we performed molecular simulations to explore the permeation of a water-ethanol mixture using a new type of Janus GO membranes with different orientations of oxidized and pristine surfaces. The results indicate that the oxidized upper surface endows the GO membrane with considerable water-capture capability and the in-built oxidized interlayer promotes the effective vertical diffusion of water molecules. Consequently, using the optimized Janus GO membrane, infinite water selectivity and outstanding water flux (∼40.9 kg·m−2·h−1) were achieved. This study contributes to explaining the role of oxidized regions in water permeation via GO membranes and suggests that Janus GO membranes could be used as potential candidates for water-ethanol separation.

A series of Co–Ce/Sepiolite (SEP) catalysts were prepared by surfactant-assisted coprecipitation route and subsequently evaluated for hydrogen production from ethanol steam reforming. The effects of the types and quantities of surfactants such as Cetyltrimethyl Ammonium Bromide (CTAB) and Polyvinyl Pyrrolidone (PVP) on catalysts microstructures were investigated by means of N2 adsorption-desorption, XRD, H2-TPR, Raman, XPS, SEM, and TEM. The results demonstrated that the function of surfactants complexation with Co/Ce precursors enlarged the metal interparticle distance, led to the surface enrichment of Co/Ce atoms and provoked diverse Co–Ce interfaces, which could both enhance the reforming behavior and restrain the amorphous coke during reaction. Meanwhile, the optimal complexation effect of CTAB on Co–Ce/SEP-C0.4 (CTAB:Mδ+ = 0.4) gave it superior reducibility, surface content of Co/Ce atoms and relative abundance of oxygen vacancies. Consequently, Co–Ce/SEP-C0.4 presented the best ethanol conversion (96.2%), hydrogen yield (77.9%) and the uppermost catalytic stability (100 h) during ESR reaction. In addition, the scatter modes of surface Co/Ce particles and forms of Co–Ce interfaces significantly depended on surfactant types.

CoCrCuFeNiVx high-entropy alloy was prepared by mechanical alloying method. X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM), Energy-Dispersive Spectroscopy (EDS) and Differential Scanning Calorimetry (DSC) were used for different samples. The crystal structure, microstructure, composition and thermal properties were studied with conclusions below. After ball milling time reaches 21 h, CoCrCuFeNiV0.6 consists of two phases (FCC1+FCC2). After adding V, the element distribution is more uniform and the complete melting temperature of the alloy decreases with increasing V content. Also, after CoCrCuFeNiV0.6 ball milling for 21 and 27 h, the alloy material powder showed the phenomenon of amorphous transition. Mechanical alloying degree of CoCrCuFeNiV0.8 is the highest when the ball milling time is 15 h. The mechanical alloying degree tends to be fixed after 21 h in the case of CoCrCuFeNiV0.6.

Fluid flow in tight formations deviates significantly from that in conventional reservoirs due to the micro/nano pores and high confining pressure; non-linear flow occurs at low displacement pressure gradients. The effects of boundary layer and media deformation on fluid flow cannot be ignored. In this paper, a stochastic network model with anisotropic topology is firstly constructed to represent the complex structures of tight formations. Subsequently, a series of network models with different physical scales are generated to obtain the representative elementary volume (REV). Based on the representative network model, a pore network flow model coupling the boundary layer effect with media deformation is developed. Iterative methods are proposed to solve the strong nonlinear mathematical model. Microtube experiments with different radii and three corresponding representative networks with different distributions of throat radii are employed to verify the accuracy and reliability of the numerical results. After the validation, pore scale flow regularity considering the boundary layer effect and media deformation of tight formations is obtained. Furthermore, the factors influencing pore scale flow, such as the effective stress, aspect ratio, coordination number and fluid viscosity, are studied. The results show that pore scale flow velocity considering the boundary layer effect and media deformation is smaller than that without considering the two mechanisms. Nonlinear flow occurs at low displacement pressure gradients because of the boundary layer effect, and media deformation aggravates the nonlinear phenomenon. Similarly, the absolute permeability also decreases when the two mechanisms are considered. It is no longer constant when boundary layer effect is taken into consideration, which increases with increasing displacement pressure gradient and reaches a plateau when the displacement pressure gradient is large enough. The effects of different factors on pore scale flow considering boundary layer effect and media deformation differ from their roles in conventional flow network models. Although the absolute permeability increases with decreasing aspect ratio and increasing coordination number, the value is far smaller than that without considering the two mechanisms because they result in the compression of the effective flow space. Additionally, the absolute permeability no longer remains unchanged when the variation of fluid viscosity is included. This indicates that the absolute permeability considering the boundary layer effect is not only affected by the pore structures but also the fluid viscosity. The methodology developed in this work provides a novel way to study the effects of boundary layer and media deformation on pore scale flow. The results provide new insights into fluid flow in tight formations.

In this paper, 3-isocyanatepropyl triethoxysilane (IPTS) was synthesized using one-pot reaction using 3-aminopropyl triethoxysilane (APTES) and triphosgeneas as the raw materials. IPTS was then reacted with three kinds of perfluoroalkyl alcohol to obtain 3-(1H,1H,2H,2H-perfluoroalkoxyamidepropyl)-triethoxysilanes with different fluoroalkyl chain lengths. The silicon wafer was etched to obtain an active and coarse surface followed by coating with self-assembled monolayer (SAMs) using fluoroalkylsilane as materials. AFM were used to reflect the variation of the surface morphologies and roughness of self-assembled films before and after coating. ATR-IR test indicated that a combination of possible bonding forms the SAMs. EDS was used to characterize the distribution of the elements on the SAMs. The result of contact angle testing and surface energy counting showed that the SAMS have good water- and oil repellency, which improved with the increment of fluoroalkyl chain length. XPS were used to characterize the change of surface element content of SAMs before and after heat treatment, which resulted in the microphase separation on the film surfaces and made the fluoroalkyl migrate from the internal of the monolayer to the outermost surface. After heating, the fluoroalkyl accumulated on the surface, which lowered the surface energy further and obtained the better water- and oil repellency.

The paper describes the preparation of Ni/xLa-SEP catalysts selected low-cost clay minerals as support that possess high catalytic performance for steam reforming of phenol-ethanol (SRPE) to sustainably produce hydrogen. The catalysts were characterized using inductively coupled plasma optical emission spectrometry (ICP-OES), N2 adsorption-desorption, X-ray diffraction (XRD), H2 pulse chemisorption, high-resolution transmission electron microscopy (HRTEM), hydrogen temperature programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The results demonstrated that the addition of La reduced the active metal size and increased the active metal surface of the Ni/SEP catalyst. The Ni/10La-SEP catalyst exhibited the smallest active metal size (5 ± 0.5 nm) and highest active metal surface area (12.7 m2/gcat.). As expected, Ni/10La-SEP presented the highest carbon conversion and H2 yield (92.1 and 87.6%, respectively) during SRPE reactions. Moreover, the La addition enhanced the steam reforming (SR) of CH4 and water-gas shift (WGS) reactions and successfully suppressed the sintering and coking of the Ni/SEP catalyst.

Revealing the sensitivity and selectivity of the Raman enhancement mechanism is extremely significant for disease diagnosis, environmental surveillance, and food safety supervision. In this study, chemical erosion copper triangle plates (CTPs) were employed as SERS substrate to detect the rhodamine B (Rh B) probe molecule at different etching times. A simple and cost-effective method affords unique insights into the surface enrichment of analytes, which could facilitate the high-performance SERS analysis of numerous analytes. The relationship between the Raman intensity and the concentration of Rh B follows the Freundlich model, which means that the wet-etching surface can create SERS-active site attachment Rh B molecules on the CTPs. The morphology of CTPs was modified by H2O2/HCl etchants; however, the composition of CTPs remained stable without oxidation. This proposes that the largest contribution to the enhancement was the hot-spots that can produce surface plasma resonance on the CTPs. The number of hot-spots can be intelligently adjusted by the artificial control of the surface morphology of metal materials, providing an unambiguous improvement in the SERS sensitivity and capability.

The main objectives of this study were to investigate the effects of boundary condition and pore size on spontaneous imbibition in tight sandstones, and to simulate and interpret the flow process. In this study, scanning electron microscopy (SEM), mercury injection capillary porosimetry (MICP) and nuclear magnetic resonance (NMR) T2 were combined to investigate the pore systems of the tight sandstone outcrop from Yanchang formation, Ordos Basin. Five parallel sets of imbibition experiments were also carried out, respectively using NMR and imbibition cell to guarantee the reliability of recovery data. Furthermore, a study was conducted to validate the linear model of recovery versus the square root of time in tight sandstones under different boundary conditions. The radial countercurrent flow encounters the linear flow, and causes mutual interference in the late stage of imbibition, which is probably the main reason for a lower recovery of all-face-open (AFO) imbibition than two-ends-closed (TEC) imbibition. Imbibition efficiency decreased with the increase in pore radii around the immovable peak, while it increased with increasing pore radii around the movable peak. The linear relationship between the imbibition recovery and the square root of time was best fitted by TEC imbibition, whereas the relationship in two-ends-open (TEO) imbibition is poor. In addition, different behaviors between TEO imbibition and the other four types indicate that gravity cocurrent flow dominates in the former one.

Superheated steam (SHS) injection in concentric dual-tubing wells (CDTW) is a new technology for offshore heavy oil recovery. Firstly, compared with conventional saturated steam injection in single-tubing wells, the key advantages of SHS injection in CDTW for heavy oil recovery are introduced. Secondly, a novel mathematical model is proposed to analysis the heat transfer characteristics of SHS flow in offshore CDTW. Then, based upon the validated model, type curves of SHS flow in offshore CDTW are analyzed in detail. The results show that: (1). The heat exchange between the integral joint tubing (IJT) and annuli has a significant influence on SHS temperature and superheat degree in each tubing. (2). More heat get lost when the seawater starts to flow, and the heat loss rate in the sea section of the wellbores is larger than that in the formation section of the wellbores. Moreover, in order to flexibly use the model in practice, the key intrinsic flow characteristics of SHS in offshore CDTW are unraveled. It is found that: (1). The SHS temperature increases at first but turns to decrease with the continuous increase of injection rate due to the fact that the drop of SHS pressure gradually replaces heat losses as the dominant factor on temperature change. (2). The superheat degree at well bottom always increases with the increase of injection rate. This paper presents a basic reference for engineers in heat loss evaluations as well as performance estimations of SHS flow in offshore CDTW.

A series of Mg-modified mesostructured Ni/Attapulgite (Ni/xMg-ATP, x = 0, 5, 10, and 20 wt%) have been produced by a co-precipitation method. The textural and physicochemical properties of as-prepared precursors and derived catalysts were characterized by N2 physical adsorption analysis, low- and wide- angle XRD, ICP-OES, H2 pulse chemisorption, SEM/EDX-mapping, TEM, FT-IR, H2-TPR and NH3-TPD. From N2 physical adsorption analysis, all synthesized catalysts possessed unique mesostructure, resulting in the high metal dispersion and interaction between active metal and support as proven by XRD, FT-IR, SEM/EDX-mapping, TEM, and H2-TPR. These properties became more distinct for Ni/10Mg-ATP sample, which had highest active metal surface area (0.69 m2/gcat) related to the smallest Ni crystal size (9.5 ± 0.1 nm), the most uniform nickel particle size and the highly dispersed Ni metal (20.2%), accompanying with highest nickel-ATP interaction. These excellent properties made it show the highest ethanol conversion (100%) and H2 yield (96.7%) and the longest stability (50 h), during ethanol steam reforming (ESR) under the T = 973 K, S/C = 1.5, and GHSV = 19,200–19,400 h−1. Meanwhile increasing temperature was positive effect for ethanol conversion and inhibiting the selectivity to hydrocarbon (such as CH4 and C2H4). In addition, the product selectivity was also considered to investigate the influence of Mg on catalytic performance. Obviously, the C2H4 selectivity (

This paper explores the applicability of nuclear magnetic resonance (NMR) technology on pore size distribution (PSD) and movable fluid distribution (MFD) in tight sandstones. Centrifugation experiments and NMR tests are performed on saturated samples. The fluid changes in pores corresponding with three different types of NMR T2 distribution after each centrifugation is then analyzed. In addition, a new method to determine the conversion factor from NMR T2 distribution to PSD is developed. In comparison with the PSD obtained by mercury intrusion porosimetry, the new method is more suitable for PSD calculation in tight sandstones. Afterward, the optimum centrifugal force to determine the threshold radius for fluid flow is obtained. On the basis of this, we analyze MFD in tight formation. Through study, the following results are arrived at: patterns of NMR T2 distributions of outcrop and subsurface cores at water saturation condition can be classified into three types (I, II, and III). Among which, type I an...

A series of Ni Cu bimetallic catalysts supported on sepiolite (Ni x Cu y /SEP) were prepared by co-precipitation method. The all as-prepared catalysts were characterized by using XRD, FT-IR, H 2 -TPR, and TEM. The results shown the Ni Cu alloys were successfully synthesized in bimetallic catalysts, and the addition of Cu promoter decreased the particles size, improved the redox ability and metal dispersion of bimetallic catalysts. Specially, the Ni 1 Cu 0.25 /SEP catalyst exhibited the smallest particles (10.2 nm) and highest metal dispersion (8.2%). In addition, the catalytic performance of prepared catalysts was evaluated during the mixture of phenol and ethanol steam reforming (PESR) reaction under the following conditions: steam to carbon ratio (S/C) = 1, WHSV = 3.2 h −1 and different temperatures (550 °C and 650 °C). The experimental results shown the high temperature was positive for increasing carbon conversion and H 2 yield. Moreover, the Ni 1 Cu 0.25 /SEP catalyst exhibited the highest carbon conversion (83.5%) and H 2 yield (67.5%) with relating to the lowest CH 4 selectivity (8.8%), which was attributed to the formation of Ni Cu alloy and the smallest particle size in Ni 1 Cu 0.25 /SEP catalyst, leading to inhibit methanation reaction and enhance the steam reforming (SR) of methane. Additionally, the effect of steam S/C ratios (1, 5, 8) on the carbon conversion and H 2 yield over Ni 1 Cu 0.25 /SEP was also tested at 650 °C, it shown that the carbon conversion was increased with the increase of S/C. Meanwhile, the test of stability was carried out over different catalysts at 650 °C. It found that the Ni 1 Cu 0.25 /SEP catalyst exhibited the outstanding stability during 24 h on steam, while the Ni 1 Cu 0 /SEP and Ni 0 Cu 1 /SEP shown rapidly deactivation after 10 h on steam. In order to illuminate the deactivation mechanism, the spent catalysts after 24 h of reaction were also characterized by XRD, TEM and TGA. The results shown Ni 1 Cu 0.25 /SEP catalyst exhibited smaller amount of carbon deposition in comparison with Ni 1 Cu 0 /SEP and Ni 0 Cu 1 /SEP catalysts, suggesting that the formation of Ni Cu alloy plays an important role in resisting to coke formation.

As an important technology in improving oil recovery, CO2 miscible flooding has achieved great success in many oil fields. However, studies on CO2 transport in porous media are mostly based on equilibrium adsorption in one-dimensional displacement where rate-controlled adsorption is not taken into consideration. In this work, we develop a radial convection–dispersion model, which simultaneously combines rate-controlled adsorption, convection, and dispersion. Based on this model, four dimensionless groups representing CO2 dispersion, adsorption capacity, flow rate, and kinetic rate groups are proposed for the first time. Subsequently, the Barakat–Clark forward and backward difference methods are combined to solve the mathematical model. CO2 concentration and adsorption at different positions in the porous media (including the effluent concentration and adsorption histories) are then calculated. Furthermore, the effects of the parameters on CO2 transport behavior are studied in detail. The results reveal that CO2 gradually moves forward with the increase in the CO2 injection volume. Once CO2 reaches a certain position, its concentration there increases and an S-shaped curve is formed. Moreover, the adsorption capacity at this position also increases significantly, and the changing rate is much higher than CO2 concentration. CO2 effluent concentration grows more uniform, and the breakthrough occurs earlier with increased dispersion velocity and CO2 injection rate and decreased adsorption capacity and adsorption rate. The mathematical model developed in this study is of great importance in predicting CO2 transport behavior in radial miscible flooding.

The effects of baffle configuration, impeller type, impeller diameter ratio, and immersion depth on the critical drawdown speed and power of floating particles were investigated by experiment, and the advantageous stirred vessel was determined on the basis of the low energy consumption principle. Furthermore, the effects of system viscosity, mean solid concentration and particle size on the dispersing characteristic of floating particles were also researched with the advantageous stirred vessel. The results show that, (1) when the stirred vessel is equipped with a single baffle, the critical drawdown speed and power of floating particles are lower than those of others. (2) Among the propeller, six flat-blade disc turbine (Rushton), and six 45° pitched-blade turbine (PBT-6), the Rushton turbine has the lowest critical drawdown speed, and the down-pumping propeller (TXL) has the lowest critical drawdown power. (3) The critical drawdown speed and power are lower with a larger impeller diameter and a smaller immersion depth. (4) The critical drawdown speed and power increases with the increasing of system viscosity, mean solid concentration, and particle size. The experimental results provide useful guidelines for the advantageous design of the stirred vessel used for the dispersing of floating particles in viscous system. This article is protected by copyright. All rights reserved

The purpose of this study was to investigate the effects of microwave power and additives on the microwave-assisted pyrolysis of cotton stalk. Pyrolysis temperature profiles, product yields, and bio-oil components were analyzed. The results indicated that as the microwave power increased, so did the final temperature and heating rate. When microwave power increased from 800 to 1200 W, the yield of the solid residue decreased and gas yield increased, but the maximum bio-oil yield of 26.7% was achieved under a microwave power of 1000 W. All three of the additives (NaOH, Na2CO3, and H3PO4) increased the yields of solid residue and gas, while the yield of the bio-oil decreased. Gas chromatography-mass spectrometry (GC-MS) analysis indicated that the main components of bio-oil from microwave-assisted pyrolysis of pure sample were acetol, furfural, 2-methoxy-phenol, and 4-methyl-2-methoxy-phenol. Sodium hydroxide and sodium carbonate (NaOH and Na2CO3) greatly favor the formation of acetol. Phosphoric acid (H3PO4) remarkably promoted the formation of furfural and 4-methyl-2-methoxy-phenol, while H3PO4 inhibited the formation of acetol.

The catalyst regenerability in steam reforming is vital for achieving the process maturity and commercialization. This work focused on the regenerability of two catalysts containing Co–Al spinel phase during successive reaction-regeneration cycles of simulated bio-oil steam reforming. The Co/sepiolite and Co/Al2O3 derived spinel catalysts were prepared via a thermal-driven solid phase reaction. The catalyst testing cycles consisted of reaction stages performed at 700 °C and subsequent regeneration treatments, which were divided into a coke combustion at 900 °C and a reduction at 800 °C. The deactivation and reproducible performances of catalysts have been ascertained by characterizing the synthesized, deactivated and regenerated catalysts by XRD, TEM, H2-TPR, XPS, Raman and TGA. The results showed that the low activity of Co/Al2O3 was not recovered by regeneration treatments, but attenuated rapidly in subsequent reaction stages due to the high Co–Al spinel crystallinity and deteriorative reducibility. In Co/SEP, the reforming behavior was not fully recovered by coke combustion, correlating with an incomplete restoration of the original spinel structure and an accumulation of cobalt oxides. The recovery of the initial activity and a preferable durability in subsequent reaction stages was attributed to the alleviation of Co sintering after regeneration.

Extensive attentions have been paid to develop steam reforming of bio-oil, which was considered as one of the sustainable technologies for producing eco-friendly next-generation energy sources, such as syngas and hydrogen. In this work, the novel catalysts consisted of CoAl2O4 spinel and Co-phyllosilicate are facilely manufactured from xCo/Sepiolite (xCo/SEP) precursors and their catalytic performance has been studied in steam reforming of simulated bio-oil (SRSB). The effects of Co content on the microstructures and physicochemical properties of catalysts are analyzed by various characterizations such as N2 adsorption-desorption, XRD, FTIR, H2-TPR, HRTEM and XPS. The results reveal that the CoAl2O4 phases in these catalysts are evolved gradually from Co-lean nonstoichiometric Co1−xAl2O4−x to Co-rich CoAl2O4 structure with increasing Co loading, subsequently accompanying with the formation Co-phyllosilicate species (CPS) when the Co content exceeds 10 wt%. Among them, calcined 15Co/SEP sample with optimal configuration of Co-Al spinel and CPS leads to its reduced-counterpart possesses fine Co metal nanoparticles, abundant defective Co-Al-spinel and metal-support interface sites. It therefore presents the highest carbon conversion (95.7%) and H2 yield (68.8%) in activity experiment and a slight deactivation in 50 h of stability test during SRSB. The analyses of TG-DSC, XRD and HRTEM are conducted on used catalysts and discover xCo/SEP-derived catalysts exhibit promising coke resistance and metal sintering is the major issue for catalyst deactivation, which mainly caused by particle migration and coalescence mechanism due to the further reduction of CPS.

Due to micro-nanopores in tight formation, fluid-solid interaction effects on fluid flow in porous media cannot be ignored. In this paper, a novel model which can characterize micro-fluid flow in micro scales is proposed. This novel model has a more definite physical meaning compared with other empirical models. And it is validated by micro tube experiments. In addition, the application range of the model is rigorously analyzed from a mathematical view, which indicates a wider application scope. Based on the novel model, the velocity profile, the average flow velocity and flow resistance in consideration of fluid-solid interaction are obtained. Furthermore, the novel model is incorporated into a representative pore scale network model to study fluid-solid interactions on fluid flow in porous media. Results show that due to fluid-solid interaction in micro scales, the change rules of the velocity profile, the average flow velocity and flow resistance generate obvious deviations from traditional Hagen-Poiseuille’s law. The smaller the radius and the lower the displacement pressure gradient (∇P), the more obvious the deviations will be. Moreover, the apparent permeability in consideration of fluid-solid interaction is no longer a constant, it increases with the increase of ∇P and non-linear flow appears at low ∇P. This study lays a good foundation for studying fluid flow in tight formation.

A coaxial mixer meeting the actual demand of a system with high and variable viscosity is investigated. It has an outer wall-scraping frame and a double inner impeller consisting of a four-pitched-blade turbine and Rushton turbine. The power consumption and flow field characteristics of the coaxial mixer in laminar and transitional flow are simulated numerically, and then the distribution of velocity field, shear rate and mass flow rate are analyzed. The simulation results indicate that the outer frame has little effect on the power consumption of the double inner impeller whether in laminar or transitional flow, whereas the inner combined impeller has a great effect on the power consumption of the outer frame. Compared with the single rotation mode, the power consumption of the outer frame will decrease in co-rotation mode and increase in counter-rotation mode. The velocity, shear rate and mass flow rate are relatively high near the inner impeller in all operating modes, and only under double-shaft agitation will the mixing performance near the free surface be improved. In addition, these distributions in the co-rotation and counter-rotation modes show little difference, but the co-rotation mode is recommended for the advantage of low power consumption.

Based on the Gidaspow model, the distributions of velocity, turbulence intensity, and solid concentration in stirred vessels equipped with a down-pumping propeller (TXL),a six flat-blade disc turbine (Rushton), or a down-pumping six 45° pitched-blade turbine (PBTD-6) in a viscous system were simulated. The power curve of the TXL propeller and the dimensionless solid concentrations of one sampling point in the vessel at different agitation speeds were obtained by simulation and experiment, which were in good agreement with each other. The results showed that: (1) both the tangential velocity and turbulence intensity on the liquid surface caused by a Rushton turbine were the highest of the three conditions at the same agitation speed; (2) the turbulence intensity on the azimuth of 90° behind the baffle near the shaft on the liquid surface was relatively larger than that in other regions; (3) the uniformity of solid concentration distribution in the stirred vessel equipped with a Rushton or PBTD-6 turbine was better than that with a TXL impeller at the same agitation speed.

The steam reforming of acetic acid (SRA) was carried out in a fixed-bed tubular reactor with Ni-Fe/ceria-palygorskite (CPG) catalysts. The as-prepared catalysts were analyzed by N2 adsorption-desorption, scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS), H2 temperature programmed reduction (H2-TPR), and X-ray diffraction (XRD). The results of H2-TPR and XRD showed that the addition of CeO2 increased the hydrogen consumption of catalysts and the interaction force between active component (Ni-Fe alloy) and carrier. Moreover, the Ni-Fe alloys were successfully synthesized in the Ni-Fe/CPG catalysts and their crystallite sizes were decreased by adding CeO2. In addition, these catalysts were employed to SRA at 600 °C, GHSV = 14427 h-1 and different molar ratio of S/C. The experimental results revealed that the Ni-Fe/C0.4PG0.6 catalyst can achieve the highest yield of H2 (87%) and HOAc conversion (95%), as well as the highest stability during the process of steam SRA. Additionally, the spent catalysts were characterized by XRD, SEM, and thermogravimetric analysis (TGA). The results showed that the addition of CeO2 enhanced the stability and activity of Ni-Fe/palygorskite catalyst and reduced the coke deposition rate on the catalyst surface.

This study introduces an innovative process of generating hydrogen-rich gas from biomass through the catalytic pyrolysis of biomass in a two-stage fixed bed reactor system. Water hyacinth was used as the biomass feedstock. The effects of various factors such as pyrolysis temperature, catalytic bed temperature, residence time, catalyst, and the nickel content of the catalyst on the pyrolysis productivity were investigated and the yields of H 2 , CO, CH 4 , and CO 2 were obtained. Results showed that the high productivity of hydrogen can be obtained particularly by increasing the catalytic bed temperature, residence time, and catalysts. The favorable reaction conditions are as follows: a first-stage pyrolysis temperature of 650 °C–700 °C, a second-stage catalytic bed temperature of 800 °C, a catalytic pyrolysis reaction time of 17 min, and a nickel content of 9% (wt %).

The synthesis of Lignin Base Epoxy Resin was based on industrial alkali lignin, and lignin-based epoxy resin curing characteristics were analyzed using the thermal weight loss technology under the oxygen atmosphere conditions. In light of the infra-red analysis of raw materials, the curing reaction kinetic parameters of lignin-based epoxy resin system were calculated using the Kissinger-Crane and Flynn-Wall-Ozawa method, and the curing reaction kinetics model of lignin-based epoxy resin system was established. The results showed that the kinetic parameters obtained using two methods were approximate, which validated that the curing reaction was consistent with the principle of the first-order reaction model. Initial curing temperature Ti0=454.88 K, curing temperature Tp0=507.55 K, and terminal temperature Tf0=598.77 K of lignin-based epoxy resin system were obtained when the extrapolation method was applied.

The power consumption of a coaxial mixer consisting of an outer anchor and different inner impellers was experimentally characterized in an agitating vessel full of Newtonian fluids (highly viscous malt syrup). Meanwhile, taking the rotation mode, speed ratio, and diameter ratio between the inner and outer impellers into consideration, a novel correlation for the calculation of the total power consumption of the coaxial mixer was introduced by defining a new characteristic diameter and a new characteristic speed. The results show that the inner impeller has an obvious effect on the power consumption of the outer impeller: the power consumption of the outer impeller will decrease under co-rotation mode and increase under counter-rotation mode. The power consumption of the high-speed inner impeller accounts for a large percentage of the total power consumption and the outer impeller has little effect on it. Compared with other existing correlations, the Reynolds number calculated from the novel correlation ...

Hydrogen will be an important energy carrier in the future and hydrogen production has drawn a great deal of attention to its advantages in efficiency and environmental benefit. Catalytic steam reforming in this study was carried out in a fixed bed tubular reactor with sepiolite catalysts. Sepiolite catalysts modified with nickel (Ni) and molybdenum (Mo) were prepared using the precipitation method. Influential parameters such as temperature, catalyst, steam to carbon ratio (S/C), the feeding space velocity (WHSV), reforming length, and activity of catalyst were investigated and the yields of H2, CO, CH4, and CO2 were obtained. The result of this experiment shows that the acidified sepiolite catalyst with addition of the Ni and Mo greatly improves the activities of catalyst and effectively increases the yield of hydrogen. The favorable reaction condition is as follows: reaction temperature is 700–800 °C; S/C is 16–18; the feeding space velocity is 1.5–2.2 h−1, respectively.

In this study, a series of Fe-based catalysts loaded on MgO were prepared by a precipitation technique. And they were tested in hydrogen production from steam reforming of ethylene glycol (SRE), which was a representative model compound of fast bio-oil. The catalysts were characterized by XRD, SEM and H2-TPR analysis. The results showed that the crystalline phases of catalysts contained Fe2O3 (Hematite), Fe3O4 (Magnetite), Fe2MgO4 (iron magnesium oxide) and MgO, and morphology of MgO was changed from the rugby-ball like particles to spherical particles with the addition of Fe. In addition, the catalytic test results indicated that the 18%Fe/MgO catalyst exhibited the highest ethylene glycol conversion (∼99.8%) and H2 molar percent (∼77%) during at the following conditions: H2O/C molar ratio is 5∼7, the feeding rate is 14 mL/h and the reaction temperature at 600∼650°C. Furthermore, the 18%Fe/MgO catalyst can keep outstanding stability during SRE for 12 h.

In this research, catalytic steam reforming of acetic acid derived from the aqueous portion of bio-oil for hydrogen production was investigated using different Ni/ATC (Attapulgite Clay) catalysts prepared by precipitation, impregnation and mechanical blending methods. The fresh and reduced catalysts were characterized by XRD, N2 adsorption–desorption, TEM and temperature program reduction (H2-TPR). The comprehensive results demonstrated that the interaction between active metallic Ni and ATC carrier was significantly improved in Ni/ATC catalyst prepared by precipitation method, from which the mean of Ni particle size was the smallest (~13 nm), resulting in the highest metal dispersion (7.5%). The catalytic performance of the catalysts was evaluated by the process of steam reforming of acetic acid in a fixed-bed reactor under atmospheric pressure at two different temperatures: 550 °C and 650 °C. The test results showed the Ni/ATC prepared by way of precipitation method (PM-Ni/ATC) achieved the highest H2 yield of ~82% and a little lower acetic acid conversion efficiency of ~85% than that of Ni/ATC prepared by way of impregnation method (IM-Ni/ATC) (~95%). In addition, the deactivation catalysts after reaction for 4 h were analyzed by XRD, TGA-DTG and TEM, which demonstrated the catalyst deactivation was not caused by the amount of carbon deposition, but owed to the significant agglomeration and sintering of Ni particles in the carrier.

In this research, catalytic steam reforming acetic acid derived from the aqueous portion of bio-oil for hydrogen production was investigated by using different Ni/ATC (Attapulgite Clay) catalysts prepared by precipitation, impregnation and mechanical blending methods. The fresh and reduced catalysts were characterized by XRD, N2 adsorption-desorption, TEM and H2-TPR. The comprehensive results demonstrated that the interaction between active metallic Ni and ATC carrier was significantly improved in Ni/ATC catalyst prepared by precipitation method, and in which the mean Ni particle size was the smallest (~13 nm) resulted in the highest metal dispersion (7.5%). The catalytic performance of the three catalysts was evaluated through the process of steam reforming of acetic acid in a fixed-bed reactor under atmospheric pressure at two different temperatures, such as 550 ℃ and 650 ℃. Results showed that the Ni/ATC (PM-N/ATC) prepared by precipitation method, achieved the highest H2 yield of ~82% and little lower acetic acid conversion efficiency of ~85% than that (~95%) of Ni/ATC (IM-NATC) prepared by impregnation method. In addition, the deactivation catalysts after reaction for 4 h were analyzed by XRD, TGA-DTG and TEM, which demonstrated that the catalyst deactivation was not caused by the amount of carbon deposition, but owed to the significant agglomeration and sintering of Ni particles in the carrier.

In this paper, the nuclear magnetic resonance (NMR) technique is applied to exploring the spontaneous imbibition mechanism in tight sandstones under all face open (AFO) boundary conditions, which will benefit a better understanding of spontaneous imbibition during the development of oil & gas in tight formations. The advantages of nuclear magnetic resonance imaging (NMRI) and NMR T2 are used to define the distribution of remaining oil, evaluate the effect of micro structures on imbibition and predict imbibition recovery. NMR T2 results show that pore size distributions around two peaks are not only the main oil distributions under saturated condition but also fall within the main imbibition distributions range. Spontaneous imbibition mainly occurs in the first 6 h and then slows down and even ceases. The oil signals in tiny pores stabilize during the early stage of imbibition while the oil signal in large pores keeps fluctuating during the late stage of imbibition. NMRI results demonstrate that spontaneous imbibition is a replacement process starting slowly from the boundaries to the center under AFO and ending with oil-water mixing. Furthermore, the wetting phase can invade the whole core in the first 6 h, which is identical with the main period of imbibition occurring according to NMR T2 results. Factors influencing the history of oil distribution and saturation differ at different periods, while it is dominated by capillary imbibition at the early stage and allocated by diffusion at later time. Two imbibition recovery curves calculated by NMRI and NMR T2 are basically consistent, while there still exists some deviations between them as a result of the resolutions of NMRI and NMR T2. In addition, the heterogeneity of pore size distributions in the two samples aggravates this discrepancy. The work in this paper should prove of great help to better understand the process of the spontaneous imbibition, not only at the macroscopic level but also at the microscopic level, which is significant for oil/gas recovery in tight formations.

The components and yield of the oil obtained by co-pyrolysis of a mixture of tobacco stem and waste rubber tire powder were investigated. The results shows that 450°C is an optimal temperature in terms of liquid product yield when the reactants are mixtures of tobacco stem and waste rubber tire powder with a mass ratio of 1∶1. It is found that the liquid product from co-pyrolysis contains less water and oxygen element, and meanwhile, hydrocarbon content increases to some degree compared with that from pyrolysis of solo pyrolysis of tobacco stem, which means the oil from co-pyrolysis is improved. However, how to improve the liquid product quality further and how to control the hazardous element emissions via co-pyrolysis needs still further studies.

Acetic acid was chosen as a model compound of fast pyrolysis bio-oil, A series of Ni-based catalyst were prepared for gasification of acetic acid in a fixed bed by microwave heating. The experimental results indicate that the additives of MgO and CoO to the Ni/Dolomite can improve the catalyst selectivity obviously, at the same time, Ni/Dolomite catalyst can reduce the carbon deposition rate efficiently. Here we have conducted the gasification of acetic acid with Ni/MgO- CoO-Dolomite and H2,CH4,CO,CO2 as indicator in a fixed bed by microwave heating for the purpose of obtaining some knowledge of its behavior under different conditions. The effects of the reactor temperature, feeding rate, molar ratio of H2O/C on yields of gas and composition of gaseous product have been investigated and the liquid product has been qualitatively analyzed. the optimum conditions is microwave temperature 750℃-900℃,H2O to carbon ratio 4-7 and feeding rate 2.5-3.2ml/min.