Search

Running dry reforming of methane (DRM) reaction at low-temperature is highly regarded to increase thermal efficiency. However, the process requires a robust catalyst that has a strong ability to activate both CH4 and CO2 as well as strong resistance against deactivation at the reaction conditions. Thus, this paper examines the prospect of DRM reaction at low temperature (400–600 °C) over CeO2–MgO supported Nickel (Ni/CeO2–MgO) catalysts. The catalysts were synthesized and characterized by XRD, N2 adsorption/desorption, FE-SEM, H2-TPR, and TPD-CO2 methods. The results revealed that Ni/CeO2–MgO catalysts possess suitable BET specific surface, pore volume, reducibility and basic sites, typical of heterogeneous catalysts required for DRM reaction. Remarkably, the activity of the catalysts at lower temperature reaction indicates the workability of the catalysts to activate both CH4 and CO2 at 400 °C. Increasing Ni loading and reaction temperature has gradually increased CH4 conversion. 20 wt% Ni/CeO2–MgO catalyst, CH4 conversion reached 17% at 400 °C while at 900 °C it was 97.6% with considerable stability during the time on stream. Whereas, CO2 conversions were 18.4% and 98.9% at 400 °C and 900 °C, respectively. Additionally, a higher CO2 conversion was obtained over the catalysts with 15 wt% Ni content when the temperature was higher than 600 °C. This is because of the balance between a high number of Ni active sites and high basicity. The characterization of the used catalyst by TGA, FE-SEM and Raman Spectroscopy confirmed the presence of amorphous carbon at lower temperature reaction and carbon nanotubes at higher temperature.

Dry reforming of methane (DRM) is becoming an appealing research topic because of the urgent need to minimize global warming and the demand for alternative energy resources. However, DRM commercialization and industrial scale application are limited by the deactivation of the applied catalysts. In this work, Ni-based catalysts supported on CeO2–MgO mixed oxides (0–20% CeO2 molar content) were prepared and employed in DRM. The support was synthesized via a coprecipitation method followed by impregnation of Ni metal. The catalysts prepared were characterized by X-ray diffraction, Brunauer–Emmett–Teller (BET) analysis, temperature-programmed reduction, X-ray photoelectron spectroscopy, and field emission scanning electron microscopy (FESEM) techniques. The catalytic performance of the catalysts was evaluated in a fixed-bed continuous reactor with an equimolar (CH4/CO2) ratio at 1073 K. The addition of CeO2, as a promoter to the support, altered the interaction between Ni and MgO and modulated the properties ...

Transesterification of castor oil, sunflower oil and mixture of both oils were conducted in a millichannel reactor with 1.6 mm internal diameter. The flow behavior of the sample in millichannel reactor was observed. Both of the oil was mixed from 100 mL of castor oil until 20 mL of castor oil with total amount of 100 mL solution before used in the reaction. The alkali catalyst was mixed together with methanol before entering the reactor. In this study, the behavior of the flow pattern inside the millichannel reactor was observed under fixed parameters which are 21:1 methanol-to-oil molar ratio, 5.4 wt% of KOH concentration in methanol, 180 s of residence time and 60 C of temperature. The FFA value of both the oils was less than 2 mg-KOH/g-oil. The viscosity and density of the oils were determined before and after mixing the oils. The flow behaviour of the castor oil formed parallel flow throughout the reactor while sunflower oil formed slug flow in the reactor. When the volume of castor oil is reduced from 100 mL to 20 mL, the flow behaviours of the mixture oil were changed from slug flow at upstream to parallel flow at downstream. The formation of slug flow in the reactor improved the biodiesel yield: 88.4% of FAME yield.

In this research, rubber wood sawdust (RWS) and Meranti wood sawdust (MWS) were pyrolyzed in a fixed bed drop-type pyrolyzer under an inert condition. The first part of the study is to determine the influence of pyrolysis temperature (450, 500, 550, 600, 650 °C) on the yield of pyrolysis products. Pyrolysis of these different residues generate an almost identical maximum amount of bio-oil close to 33 wt.%, but at different maximum temperature (550 °C for pyrolysis of RWS and 600 °C for pyrolysis of MWS). To evaluate the effect of biomass type on the composition and characterization of pyrolysis products, the second part involves the analyses of pyrolysis products from the maximum pyrolysis temperature. Acetic acid, tetrahydrofuran, and benzene were the main bio-oil components. The bio-oil contained high percentage of oxygen and hydrogen, indicating high water content in the bio-oil. High amount of water in bio-oil significantly reduced its calorific value. Under extensive heating, particle size of the bio-char from SEM images decreased due to breakage and shrinkage mechanisms. The major components of non-condensable gases were CO and CO2.

Torrefaction of oil palm kernel shell (PKS), one of the biomass residues from the palm oil industry, was carried out in a fixed-bed tubular reactor in the presence of oxygen and carbon dioxide at concentrations ranging from 0 to 15 vol.% (nitrogen balance). The effects of oxygen and carbon dioxide concentrations (0, 3, 9, 12, and 15 vol.%), temperature (493, 523, and 573 K) and biomass size (0.375 mm and unground) on the solid phase conversion, the energy yield and properties of torrefied biomass were investigated. The solid phase conversion increased with increasing temperature and oxygen or carbon dioxide concentration, but was not significantly affected by biomass size. The energy yield decreased with increasing oxygen or carbon dioxide concentration, but was still more than 70%. The extent of torrefaction was in the order of oxygen > carbon dioxide > nitrogen. The ‘oxidative torrefaction’ rate was extracted from the overall reaction rate. The increase in the oxidative torrefaction rate caused by oxygen was higher than that caused by carbon dioxide. Scanning electron microscope observations of the morphology of the PKS showed distinctive differences for torrefaction in nitrogen, oxygen, and carbon dioxide.

Thermogravimetric data, the Coats–Redfern free integral method, and correlation coefficients obtained by use of different reaction models were used to study the kinetic characteristics of non-catalytic and catalytic pyrolysis of biomass. Zeolite catalysts (ZSM-5, MCM-22, and ITQ-2) were mixed with the biomass in the ratio 1:10. Analysis of thermogravimetric data revealed that thermal decomposition occurred at 240–450 °C for both non-catalytic and catalytic pyrolysis of biomass. Two temperature regions, region I 240–330 °C and region II 360–450 °C, were identified and a best-fit model describing the behavior of non-catalytic and catalytic biomass pyrolysis was obtained. Addition of catalyst reduces the activation energy in first region then increases it in the second region for all reaction orders. Chemical reaction and diffusion-controlled reaction mechanisms could be kinetically characterized and enabled good description of the nature of biomass pyrolysis.

This study investigates the effect of pyrolysis temperature on the yields of char, organic compounds, water and gas. Fast pyrolysis was carried out in a fluidized bed reactor of 108 mm in internal diameter operated at 400, 450, 500 and 550 °C with nitrogen gas with flow rate of 25 L(NTP)/min. In specific the effect of temperature on the yields of known and unknown organics in bio-oil is discussed. For higher total organics, 500 oC was favorable. But higher phenol and acetic acid yields, 450 oC was preferable. The major organics include acetic acid, phenol and furfural. The minor ones include 2-methylphenol, 4-methylphenol, 4-methylnaphthalene, benzene, toluene and THF.

Transesterification of palm oil with methanol using a potassium hydroxide (KOH) catalyst to form fatty acid methyl ester (FAME) commercially known as biodiesel was performed in a millichannel reactor. In this study, a transparent Teflon tubular reactor with the inner diameter of 1.59 mm at 60 °C was carried out to produce FAME. Residence time was changed by changing the tube length and flow rate. The residence time of 69 s is required to achieve more than 88% of ester content. The relationship between ester content and flow pattern was also investigated.

Oil palm empty fruit bunch (OPEFB) fiber is a natural polymer which is potentially used as efficient adsorbents for heavy metal cations. The main objective of this research is to synthesize OPEFB grafted polyvinyl alcohol (PVA) hydrogel by using ammonium persulfate (APS) as initiator and gelatin as crosslinking agent. The grafting temperature, amounts of cross linking agent, initiator and concentration of OPEFB were manipulated in order to optimize the swelling capability of the hydrogel. Comparison of heavy metal adsorption performance between pure PVA hydrogel and optimized OPEFB-g-PVA hydrogel was evaluated by using copper ions solution. The characteristics and structure of the optimized OPEFB-g-PVA hydrogel was studied by using Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM) while Thermogravimetric Analysis (TGA) was used to study its thermal stability. The presence of band at 1088 and 1047cm-1 corresponds to C-O was observed as strong evidence of grafting. Water ...

In this research, Meranti wood sawdust (MWS) was pyrolyzed in a fixed bed drop- type pyrolyzer under an inert condition. The first part of the study is to determine the influence of pyrolysis temperature (450, 500 and 550 °C) on the yield of pyrolysis products. Pyrolysis of the waste MWS material generated the highest amount of bio-char with approximately 38 wt.% at pyrolysis temperature of 450 °C. Next, the char product (from pyrolysis at 450 °C) was analyzed to compare its characteristics with the raw MWS feedstock. The major component of the char is carbon element, significantly contributed to its high calorific value. TGA profile shows the MWS char could withstand high temperature of up to 400 °C. Under extensive heating, particle size of the bio-char from SEM images decreased due to breakage and shrinkage processes.

Oil palm empty fruit bunches activated carbon of different parts (shaggy and core) were characterized as to convert waste of oil palm-based into value added products. Conventional step processes of physical activation were performed where activation was undertaken after the pyrolysis process (carbonization-activation process). The pyrolysis temperatures applied were 400, 450, and 500°C in inert condition under nitrogen flow. For the activation process, 600, 700, and 800°C with the presence of 15%, 60%, and 100% CO 2 and holding time of 30, 60, and 120 minutes were applied. Results showed that activation temperature, CO 2 percentage and holding time did dictate the changes of activated carbon yield, carbon content, and textural properties of the activated carbon core and shaggy EFB produces. The highest yield of activated carbon was obtained from 700°C (middle temperature), 60% CO 2 (middle percentage), and 30 mins holding time (shortest). However, the highest carbon content was detected from 600°C, 60% CO2, and 60 mins of activated carbon core EFB. The size of pore determined prove that the three parameter do not correlate with each other as the bigger pore diameter was derived from 700°C, 60% of CO 2 , and 60 mins holding time. Hence, the results revealed that there are differences of activated carbon properties when we separate EFB part into its core and shaggy.