Sim Yee Chin

Catalytic Performance of Cement Clinker Supported Nickel Catalyst in Glycerol Dry Reforming

The paper reports the development of cement clinker-supported nickel (with metal loadings of 5 wt%, 10 wt%, 15 wt% and 20 wt%) catalysts for glycerol dry (CO2) reforming reaction. XRF results showed that CaO constituted 62.0% of cement clinker. The physicochemical characterization of the catalysts revealed 32-folds increment of BET surface area (SBET) with the addition of nickel metal into the cement clinker, which was also corroborated by FESEM images. Significantly, XRD results suggested different types of Ni oxides formation with Ni loading, whilst Ca3SiO5 and Ca2Al0.67Mn0.33FeO5 were the main crystallite species for pure cement clinker. Temperature-programmed reduction analysis yielded three domains of H2 reduction peaks, viz. centered at approximately 750 K referred to as type-I peaks, another peaks at 820 K denoted as type-II peaks and the highest reduction peaks, type-III recorded at above 1000 K. 20 wt% Ni was found to be the best loading with the highest XG and H2 yield, whilst the lowest methanation activity. Syngas with lower H2/CO ratios (0.6 to 1.5) were readily produced from glycerol dry reforming at CO2-to-Glycerol feed ratio (COR) of unity. Nonetheless, carbon deposit comprised of whisker type (Cv) and graphitic-like type (Cc) species were found to be in majority on 20 wt%Ni/CC catalysts.

Modeling and Simulation Study of an Industrial Radial Moving Bed Reactor for Propane Dehydrogenation Process

Abstract An accurate model is required to optimize the propane dehydrogenation reaction carried out in the radial moving bed reactors (RMBR). The present study modeled the RMBR using a plug flow reactor model incorporated with kinetic models expressed in simple power-law model. Catalyst activity and coke formation were also considered. The model was solved numerically by discretizing the RMBR in axial and radial directions. The optimized kinetic parameters were then used to predict the trends of propane conversion, temperature, catalyst activity and coke content in the RMBR along axial and radial directions. It was found that the predicted activation energies of the propane dehydrogenation, propane cracking and ethylene hydrogenation were in reasonable agreement with the experimental values reported in the literature. The model developed has accurately predicted the reaction temperature profile, conversion profile and catalyst coke content. The deviations of these simulated results from the plant data were less than 5%.

Synthesis and Characterization of Dealuminated Ultra-Stable Zeolite Y Supported Cesium Salt of Phosphotungstic Acid for the Esterification of Acrylic Acid with Butanol

Wastewater containing 10–20 wt% of acrylic acid (AA) is released from petrochemical industries during the manufacture of AA, acrylic ester, water-soluble resin and flocculants. This untreated wastewater could have detrimental effects on the environment due to its high chemical oxygen demand. Heterogeneously catalyzed esterification of this wastewater with alcohol in a reactive distillation column (RDC) could be a promising treatment method to recover AA from the wastewater. Considering the importance of a water-resistant catalyst in this method, this work has synthesized and tested a potential catalyst, cesium salt of phosphotungstic acid (CsxH3-xPW) supported on dealuminated ultra-stable zeolite Y (DUSY), for the esterification of AA with 1-butanol (BuOH). The catalysts were synthesized through impregnation using various solvents, DUSY with different compositions of silicon (Si) to aluminium (Al), compositions of cesium (Cs) and precursor loadings. The 30%(Cs1.5(IWI)H1.5PWIWI)DEE/DUSY60 was the best catalyst, giving reasonably high yield and low leaching. The BA yield obtained was 9.53% at 80°C, stirring speed of 500 rpm, catalyst loading of 10 wt% and MAA:BuOH of 1:3 for 4 h.

A comparison of entrapped and covalently bonded laccase: Study of its leakage, reusability, and the catalytic efficiency in TEMPO-mediated glycerol oxidation

Abstract This article presents the comparison for reusability and leakage between entrapped and covalently bonded laccase and their performances towards the selective oxidation of glycerol. The reusability of immobilized laccase enzyme was studied by reacting a batch of immobilized laccase with ABTS for 15 cycles. The investigation of the leakage of immobilized laccase was carried out by storing the immobilized laccase in acetate buffer solution for 32 days. The data show that the retained enzyme activities of entrapped and covalently bonded enzyme after being reused for eight cycles were well above 60% and the leakages after storing for a month in the acetate buffer at 4 °C were well below 15%. The entrapped laccase coupled with TEMPO was found to perform better and gave a two-fold higher yield of glyceraldehyde and glyceric acid in the selective oxidation of glycerol compared to covalently bonded laccase. Hence, physical entrapment of laccase would be a suitable immobilization method in the laccase-mediated selective oxidation of glycerol.