Modeling and Comparison a Thermally Coupled Reactor of Methane Tri – Reforming and Dehydrogenation of Cyclohexane Reactions for Syngas Production in Both Co- & Counter-Current Modes

The aim of this work is a comparison of different inlets (Co- and Counter-current modes) to feed a thermally coupled reactor (TCR) in producing syngas as a valuable chemical. The novel thermally coupled reactor has been designed as a double pipe reactor where tri-reforming of methane for syngas production has been considered in the exothermic side of fixed bed plug reactor, and dehydrogenation of cyclohexane reaction occur in the endothermic side. The heat generated in the exothermic part by the walls of the tube side is transferred to the endothermic section. A steady-state homogeneous one-dimensional model predicts the performance of this reactor for simultaneous production of synthesis gas and benzene in an economical approach for both co- and counter-current modes of operation. The reversed flow of cyclohexane has been considered for the counter-current flow regime. The simulation results of co- and counter-current modes of TCR and also an optimized tri-reforming of methane (OTRM) single reactor are investigated and compared with each other. The results showed that methane conversion, hydrogen yield and ${H_2}/Co$ ratio in the exothermic side of TCR reached to 91.1 %, 1.82 and 2.1 in co-current mode and 87.8 %, 1.77 and 2.3 in counter-current mode, respectively. Additionally, the results showed that cyclohexane conversion at the endothermic side of the reactor in co- and counter-current modes achieved to 98.6 % and 99.9 %, respectively. So, the results for counter-current mode showed superior performance in hydrogen and benzene production in the endothermic side of TCR. Also, Changes in various operating parameters during the reactor have been studied.

Structural Properties and Catalytic Behaviour of CrOx/TiO2 Systems

<p>The present investigation comprises of an attempt to investigate the titania supported chromia catalysts using X-ray diffraction measurements (XRD), evolved gas analysis (EGA), FT infrared spectroscopy (FTIR) and FT-Raman spectroscopic techniques with catalytic evaluation by dehydrogenation of cyclohexane. Evolved Gas Analysis shows a modified decomposition pattern than that of bulk chromia and presence of surface heterogeneity owing to the modified surface anchored chromia species formed as a result of interaction between chromia and titania. Above 773 K, Cr⁶⁺ is not stable over TiO₂ surface and the reduction of the Cr⁶⁺ to intermediate chemical states take place. XRD investigations illustrate the significance of X-ray source in examining supported chromia catalysts to study the morphological modifications of the active phase when crystalline supports are employed. FT Raman spectra reveals that on calcining the sample at 573 K, for 2 hours, the chromia phase assumes a monomerically anchored molecular state. Longer calcination time (6 hours) at the same temperature, leads to the diffusion of <em>in</em><em> </em><em>situ </em>formed Cr³⁺ ions into the anatase lattice. On calcination at 973 K for 6 hours, amorphous chromia phase is no more stable on TiO₂ support resulting inagglomeration leading to the germination of microcrystalline α–Cr₂O₃. Evaluation of catalytic performance of above catalysts by dehydrogenation of cyclohexane confirms the fact that diffusion of part of Cr³⁺ species into the bulk of anatase phase occurs under reaction conditions.</p>