Iranian Journal of Chemical Engineering (IJChE)

Abstract One of the effective catalysts for hydrogen purification and production via medium temperature shift reaction, is Cu-Ce solid solution. Cu0.1Ce0,9O1.9 was produced using co-precipitation method and then was utilized as support for 5Cu/Ce0.9Cu0.1O1.9 catalyst which was synthesized employing wet impregnation method. X-ray diffraction (XRD) analysis showed that crystalline sizes of Ce0.9Cu0.1O1.9 and 5Cu/Cu0.1Ce0,9O1.9 were 9.22 and 18.33 nm, respectively. The Catalysts were evaluated in medium temperature shift reaction at 300-390 °C and at gas hourly space velocities (GHSV) of 12000 and 30000 h-1, in a fixed bed reactor. Due to higher concentration of Cu and synergic positive effects of both active metal and support, 5Cu/Cu0.1Ce0,9O1.9 catalyst showed better performance. It was also concluded that, because of low residence time at high levels of GHSV, increasing GHSV leads to decrease CO conversion. Then 5Cu/Cu0.1Ce0,9O1.9 was evaluated in microchennel reactor in 2 GHSVs of 12000 and 30000 h-1 and results were compared with the fixed-bed reactor. It can be concluded that microchannel reactor is better in higher GHSVs (lower residence time of gas flow). A microchannel reactor provides a high surface-to-volume ratio and gases pass over the thin layer of catalyst on the coated plates. Hence, due to the better access to the catalytic bed, the reactants react even in a short time, which improves the microchannel performance compared to the fixed bed reactor

Abstract e"> The CeMnO2 supports were prepared via co-precipitation method by ammonia as precipitating agent. The CuO/CeO2 and CuO/Ce(1-x)MnxO2 (x=0.1, 0.3 and 0.5) catalysts were synthesized by wet impregnation method. The physicochemical properties of the prepared CuO/Ce(1-x)MnxO2 catalysts were characterized by N2 adsorption-desorption, powder X-ray diffraction (XRD) and programmed H2 temperature reduction (H2-TPR). The effects of Cu and Mn loading were investigated on the catalytic performance. The findings illustrated that the 7% CuO/Ce0.9Mn0.1O2 catalyst shows high activity for CO-PrOx. The high activity of 7% CuO/Ce0.9Mn0.1O2 catalyst was ascribed to high surface area of the support, synergetic effects of CuO and CeO2 and increases of the mobility of lattice oxygen in ceria by addition of MnO2. The effects of presence of H2O in the reaction feed stream, oxygen to CO ratio (λ) and gas hourly space velocity (GHSV) on the catalytic activity of 7% CuO/Ce0.9Mn0.1O2 were evaluated. It was found that the best performance of 7% CuO/Ce0.9Mn0.1O2 catalyst was obtained at λ=2, GHSV=20000 h-1 and in addition, the presence of H2O had negative effects on the activity of the catalyst. In the long term stability test, nearly 100% CO conversion was maintained for 50 h at 120°C with 70-80% CO2 selectivity.

Abstract Waste cooking oil (WCO) is being generated large scale all over the world; hence it has devised serious problems of its waste management. Organised collection of WCO in voluminous quantity is mainly used for the production of biodiesel. Most researchers focus primarily on the biodiesel generation from WCO, although other applications are also important and require attention. Objective of this review article is to highlight most of the aforementioned possible applications of WCO which may help in its utilization apart from biodiesel. It can be processed to obtain pyrolytic oil, hydrogen gas, biodiesel or electricity production by direct burning. Applications like combined heat and power generation (CHP) can utilize WCO with utmost efficiently. It can also be processed chemically to obtained biodegradable polyurethane sheets, greases, biolubricants, soaps and alkyd resins. Properly purified and sterilized WCO can be used as a carbon source in fermentation processes for the production of rhamnolipid biosurfactant and polyhydroxybutyrate (PHB). Waste cooking oil therefore can be considered as a potential waste which can be utilized as energy source and raw material for chemical or biological processes.

Abstract In the present study, the main focus was on plasma pyrolysis and gasification of organic waste, specifically polyethylene and cotton waste and exploring the energy recovery possibilities from the gases obtained after the plasma pyrolysis and gasification. In pyrolysis the gases formed are Syn gas (H2 + CO), CH 4, higher hydrocarbons along with soot particles. The waste is disintegrated using thermal plasma (which is generated using graphite plasma torch) in oxygen starved environment (pyrolysis) and also in partial oxidation condition (gasification). Experiments have been carried out by varying pyrolysis chamber temperature from 500 0C to 700 0C and polyethylene and cotton are fed into the pyrolysis chamber. It has been observed that plasma pyrolysis of polyethylene in the temperature range of 500 to 700 0C yields H 2 as main component around 30-40% volume basis along with CO, CO2, CH 4, C2H 6, C2H 4, C2H 2 and soot particles whereas pyrolysis of cotton, on the other hand provides less H 2 around 15-20 %. However, it has also been observed that in plasma gasification H2, CO, CH 4 content in the exhaust gases reduces to some extent (2-5%). The theoretical and experimental energy recovery comparisons have also been carried out.

Abstract Eventual realization of a hydrogen economy requires cheap and readily available hydrogen sources and a technology to convert them into pure hydrogen in an efficient and sustainable manner. The objective of this paper is the computational investigation of the hydrogen production through thermal decomposition of sour natural gases containing CH 4 and H 2S inside a solar reactor. In this study a solar reactor has been used to absorb solar power and allow it to concentrate in a graphite nozzle in the middle of the reactor and transfer it to a flow reactant thereafter. From an economical standpoint, the main issue is the production of two valuable products, hydrogen (H 2) and a high-value nano-material of carbon. The effects of H 2S to CH 4 feed ratio and reactor temperature on hydrogen, carbon black, S2 and CS 2 formation are investigated. The results show complex behavior in the products because of the difference in CH 4 and H 2S pyrolysis temperatures. It can be seen that for H2S/CH 4>2, the yields of H2 and CS 2 reach a local and global maximum at H2S/CH 4=5, respectively. A comparison performed between the presented results and the results of Towler and Lynn, and Abanades demonstrates a good agreement.

Abstract Catalytic combustion of lean premixed mixtures of biogas/air and biogas/hydrogen/air on Pt in a packed bed reactor has been investigated using detailed surface chemistry. Non-equilibrium, adiabatic and one dimensional flow assumptions have been adopted for simulation of the reactor. The interaction between two phases of porous medium is incorporated into the model via heat and mass transfer factors. Radiation heat transfer has been taken into account using effective thermal conductivity. All thermo-physical properties of the gas phase are considered to be temperature and concentration dependent. Two energy equations for two phases of the porous medium along with species transport equations are solved in the model. A mechanism of multi-step surface reactions, suitable for oxidation of lean mixture of methane/air, has been adopted from literature and employed for simulations. This mechanism includes 36 single step reactions with 11 surface and 6 gas phase species. Simulations have been conducted for oxidation of different biogas/air mixtures for the inlet temperature range of 700K to 900K at atmospheric pressure. The effect of the addition of hydrogen to the biogas/air mixtures has also been investigated. It is shown that hydrogen improves oxidation of methane.