Current Issue : July - September Volume : 2019 Issue Number : 3 Articles : 5 Articles
Ni catalysts supported on SiO2 are prepared via a facile combustion method. Both glycine\nfuel and ammonium nitrate combustion improver facilitate the formation of much smaller Ni\nnanoparticles, which give excellent activity and stability, as well as a syngas with a molar ratio\nof H2/CO of about 1:1 due to the minimal side reaction toward revserse water gas shift (RWGS) in\nCH4 dry reforming....
This work presents studies on the co-combustion of sludge and wheat straw (30 wt %\nsludge + 70 wt % wheat straw). Prior to the combustion experiment, thermogravimetric analysis was\nperformed to investigate the combustion characteristic of the blended fuel. Results indicated that the\nblended fuel could remedy the defect of each individual component and also promote the combustion.\nCo-combustion experiments were conducted in a lab-scale vertical tube furnace and the ash samples\nwere analyzed by Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES), X-ray\nDiffraction (XRD), and Scanning Electron Microscope (SEM). Thermodynamic calculations were also\nmade to study the interactions that occurred. Addition of sludge could raise the melting point of\nwheat straw ash and reduce the slagging tendency. Co-combustion also restrained the release of K\nand transferred it into aluminosilicate and phosphate. Transfer of Pb and Zn in the co-combustion\nwas also studied. The release and leaching toxicity of the two heavy metals in the co-combustion\nwere weakened effectively by wheat straw. PbCl2(g) and ZnCl2(g) could be captured by K2SiO3 in\nwheat straw ash particles and generate silicates. Interactions that possibly occurred between K, Zn,\nand Pb components were discussed at the end of the paper....
Abstract: Fluidized bed applications where the bed material plays an active role in chemical reactions,\ne.g. chemical looping combustion, have seen an increase in interest over the past decade. When these\nprocesses are to be scaled up to industrial or utility scale mass transfer between the gas and solids\nphases can become a limitation for conversion....Confined fluidized beds were conceptualized for other\npurposes in the 1960â??s but are yet to be applied to these recent technologies. Here it is investigated if\nthey can prove useful to increase mass transfer but also if they are feasible from other perspectives\nsuch as pressure drop increase and solids throughflow. Four spherical packing solids, 6.35â??25.4 mm\nin diameter at two different densities, were tested. For mass transfer experiments the fluidizing air\nwas humidified and the water adsorption rate onto silica gel particles acting as fluidizing solids\nwas measured. Olivine sand was used in further experiments measuring segregation of solids and\npacking, and maximum vertical crossflow of solids. It was found that mass transfer increased by\na factor of 1.9â??3.8 with packing solids as compared to a non-packed reference. With high-density\npacking, fluidizing solids voidage inside the packing was found to be up to 58% higher than in a\nconventional fluidized bed. Low density packing material favoured its flotsam segregation and with\nit higher fluidization velocities yield better mixing between packing and fluidizing solids. Maximum\nvertical cross-flow was found to be significantly higher with low density packing that fluidized,\nthan with stationary high-density packing. Conclusively, the prospect of using confined fluidized\nbeds for improving mass transfer looks promising from both performance and practical standpoints....
Fe/Beta catalysts were used for the selective catalytic reduction of nitric oxide with\npropylene (C3H6-SCR) under lean-burn conditions, which were prepared by liquid ion-exchange\n(LIE), solid-state ion-exchange (SIE), and incipient wet-impregnation (IWI) methods. The iron species\non Fe/Beta were characterized and identified by a combination of several characterization techniques.\nThe results showed preparation methods had a significant influence on the composition and\ndistribution of iron species, LIE method inclined to produce more isolated Fe3+ ions at ion-exchanged\nsites than IWI and SIE method. C3H6-SCR activity tests demonstrated Fe/Beta(LIE) possessed\nremarkable catalytic activity and N2 selectivity at temperature 300â??450 Degree C. Kinetic studies of\nC3H6-SCR reaction suggested that isolated Fe3+ species were more active for NO reduction, whereas\nFe2O3 nanoparticles enhanced the hydrocarbon combustion in excess of oxygen. According to the\nresults of in situ DRIFTS, more isolated Fe3+ sites on Fe/Beta(LIE) would promote the formation of\nthe key intermediates, i.e., NO2 adspecies and formate species, then led to the superior C3H6-SCR\nactivity. The slight decrease of SCR activity after hydrothermal aging of Fe/Beta(LIE) catalyst might\nbe due to the migration of isolated Fe3+ ions into oligomeric clusters and/or Fe2O3 nanoparticles....
This paper is part of a sustainable development approach, the aim being to develop\na thermochemical energy recovery path while reducing the amount of tomato waste issued\nfrom agro-industrial units. The thermal process may contribute to an environmentally friendly\nmanagement and help tomato processing industries creating new economic profitable circuits in\nan increasingly competitive context. The adopted approach was to follow the operating conditions\nneeded for a complete thermal degradation through a thermal and kinetic analyses. The results\nof the tomato waste characterization confirmed their suitability to a thermochemical processing\nwith high volatiles and fixed carbon and interesting high heating values comparable to sawdust\nbiomass. We were able to isolate of the decomposition domains and extract kinetic parameters.\nThree kinetic models were applied; Flynnâ??Wallâ??Ozawa (FWO) simulated the best the combustion\nprocess..........
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