METHANE DRY REFORMING OVER MONTMORILLONITE SURFACE MODIFICATION SUPPORTED NICKEL CATALYST

Dry reforming of methane has been taken an interest in research and development for converting greenhouse gases (CH4 and CO2) into hydrogen (H2) and carbon monoxide (CO). Clay has been considered as promising materials because of their structure, low cost and wide availability. Different surface modifications of clay directly affect the performance of catalyst in term of CH4 and CO2 conversion. This research studied nickel loaded on montmorillonite (MMT) clay support with different surface modifications on the activity in dry reforming of methane in fixed-bed reactor with reactant gases flow rate of 60 ml/min (CH4:CO2 of 1) at reaction temperature ranges of 500 – 800°C. Montmorillonite clay support with different surface modifications including trimethyl stearyl ammonium (MMT-TSA), dimethyl dialkyl amine (MMT-DDA), methyl dihydroxy-ethyl hydrogenated tallow ammonium (MMT-MDA) and aminopropyltriethoxysilan and octadecylamine (MMT-AO) were investigated. As the results, the performances of all catalysts increased with increasing reaction temperature because this reaction is endothermic reaction. Among them, Ni/MMT-TSA catalyst exhibited the highest CH4 and CO2 conversions at all reaction temperatures due to its high surface area, and high metallic surface area

Hydro-Fractionation for Biomass Upgrading

Lignocellulosic biomass is mainly composed of three components including cellulose, hemicellulose, and lignin. A fractionation step is considered as one of the most important preliminary processes for the separation of these three components before their further utilization. Among different separation techniques, water-based pretreatments or hydro-fractionations including (a) subcritical water extraction, (b) supercritical water extraction, and (c) steam explosion have shown their promising advantages both in terms of separation efficiency and in terms of environmental friendliness. Several hydro-fractionation technologies have been developed during the last decade in which each fractionation process has different impacts on the compositional and structural features of biomass. The fractionation principle, current status, and their potential uses in the biorefinery for sugar-based chemical platform production are mainly discussed

Preparation of Porous Anhydrous MgCl2 Particles by Spray Drying Process

Polyethylene (PE) is indispensable materials in daily lives. The catalyst is necessary to produce PE. Ziegler-Natta catalysts were mostly used to produce PE which consisted of MgCl2/TiCl4 system. Polyethylene particle was reported to replicate the shape of the catalyst particles or catalyst support particles. Therefore, the MgCl2 supports need to satisfy various requirements regarding particle morphology such as shape, particle size with uniform size distribution as well as the porosity. In this research, the preparation of MgCl2 particles from irregular shape of anhydrous MgCl2 by spray drying method was studied. However, because of the hygroscopic properties of anhydrous MgCl2, all steps of experiment in this work were operated under dry N2 atmosphere. The effect of type of alcohol, ethanol, n-propanol and n-butanol as solvent which was used to dissolve MgCl2 before feeding through the spray drying on the particle properties were investigated. The amount of residual alcohol (alcoholic hydroxyl group content), morphology, specific surface area, porosity and crystallinity were determined by GC method, scanning electron microscope (SEM), N2 sorption analyzer and X-ray diffraction (XRD), respectively. The results revealed that spray drying process can produce the porous anhydrous MgCl2 particles which have rough surface, higher porosity and lower crystallinity than original anhydrous MgCl2

Mesoporous RF-Xerogels by Facile Hydrothermal Synthesis

Mesoporous resorcinol-formaldehyde (RF) xerogels were difficult to obtain by conventional sol-gel polymerization at atmospheric pressure because the resulting tenuous RF-gel structures tended to shrink or collapse during subsequent hot-air drying. To avoid this problem, costly and energy-intensive supercritical drying and freeze-drying are often used. In this work the main goal was to produce high-quality RF xerogels with good mesoporosity and high surface area by employing a hydrothermal process. The hydrogel synthesis was carried out in an autoclave at elevated temperature and pressure in order to sufficiently strengthen its network structure. The initial reactant ratio was held constant to search for most suitable hydrothermal temperature and initial pH. The experimental results showed that the reaction in the autoclave at 140ºC and initial pH of 6 could successfully produce RF xerogels with good mesoporosity (peaking pore radius rpeak = 2.38 nm), high specific surface area and large pore volume. The hydrothermal process was on the overall relatively simple, low-cost, and less time-consuming compared to the conventional atmospheric method

Unveiling the CO Oxidation Mechanism over a Molecularly Defined Copper Single-Atom Catalyst Supported on a Metal-Organic Framework

Elucidating the reaction mechanism in heterogeneous catalysis is critically important for catalyst development, yet remains challenging because of the often unclear nature of the active sites. Using a molecularly defined copper single-atom catalyst supported by a UiO-66 metal-organic framework (Cu/UiO-66) allows a detailed mechanistic elucidation of the CO oxidation reaction. Based on a combination of in situ/operando spectroscopies, kinetic measurements including kinetic isotope effects, and density-functional-theory-based calculations, we identified the active site, reaction intermediates, and transition states of the dominant reaction cycle as well as the changes in oxidation/spin state during reaction. The reaction involves the continuous reactive dissociation of adsorbed O2 , by reaction of O2,ad with COad , leading to the formation of an O atom connecting the Cu center with a neighboring Zr4+ ion as the rate limiting step. This is removed in a second activated step

Parametric Study on Microwave-Assisted Pyrolysis Combined KOH Activation of Oil Palm Male Flowers Derived Nanoporous Carbons

Oil palm male flowers (PMFs), an abundant agricultural waste from oil palm plantation in Thailand, have been utilized as an alternative precursor to develop nanoporous carbons (NPCs) via microwave-assisted pyrolysis combined potassium hydroxide (KOH) activation. The influences of relevant processing variables, such as activating agent ratio, microwave power, and activation time on the specific pore characteristics, surface morphology, and surface chemistry of PMFs derived nanoporous carbons (PMFCs) have been investigated to explore the optimum preparation condition. The optimum condition under a microwave radiation power of 700 W, activation holding time of 6 min, and activating agent ratio of 2:1 obtained the PMFC with the highest Brunauer–Emmett–Teller (BET) surface area and total pore volume approximately of 991 m2/g and 0.49 cm3/g, composed of a carbon content of 74.56%. Meanwhile, PMFCs have a highly microporous structure of about 71.12%. Moreover, activating agent ratio and microwave radiation power indicated a significant influence on the surface characteristics of PMFCs. This study revealed the potential of oil palm male flowers for the NPCs’ production via microwave-assisted KOH activation with a short operating-time condition