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Syed A. Ali,Faisal M. Almulla,B. Rabindran Jermy,Abdullah M. Aitani,Raed H. Abudawoud,Mohammed AlAmer,Ziyauddin S. Qureshi,Thamer Mohammad,Hassan S. Alasiri 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.98 No.-
Hierarchical composites of MCM-41 on zeolite Beta were synthesized by in-situ hydrothermal technique,characterized and their catalytic performance for converting heavy reformate into valuable xylenes wasevaluated. Systematic optimization of the hierarchical pore generation was carried out by varying thestrength of the alkaline solution (0.10 0.45 M NaOH) during disintegration of zeolite Beta. Thenanocomposites obtained were extruded with alumina binder and impregnated with 4.0 wt% Mo. Thecharacterization results indicate the transition of mesophase occurs from distinct disordered phase toordered/disordered and then to ordered mesophase with increasing alkaline concentration. The xyleneyield over the hierarchical composite zeolite was 1.4 times more than the parent zeolite Beta. Incorporation of a well-dispersed mild hydrogenation function (4 wt.% Mo) was advantageous inimproving the xylene yield and selectivity. The formulation prepared with moderately alkaline (0.2 MNaOH) solution exhibited optimum bimodal pore structure and improved dealkylation and transalkylationconversion resulting in a xylene yield of 33.0 wt.% and 1.7 times enhancement in xyleneselectivity over parent zeolite Beta. A 30 h stability test showed steady performance and xylene yields. Hence, a potential application of hierarchical zeolite Beta and MCM-41 composite catalysts for theconversion of heavy aromatics to produce xylenes has been successfully demonstrated.
Influence of toluene–tetramethylbenzene transalkylation on heavy aromatics conversion to xylenes
Sulaiman S. Al-Khattaf,Syed A. Ali,Mogahid S. Osman,Abdullah M. Aitani 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.21 No.1
Transalkylation of toluene–tetramethylbenzene (TeMB) over MOR and BEA was investigated at 250–400 8C. Conversion of TeMB was higher than trimethylbenzene (TMB) and toluene. Xylene yield was inthe following order: ½toluene TMB TeMB >½toluene TeMB >½toluene TMB ½toluene . Kineticmodeling for reaction network consisting of toluene–TeMB transalkylation; toluene disproportionation;and toluene–TMB transalkylation was carried out. Toluene–TeMB transalkylation rate was >50% higherthan the toluene–TMB transalkylation while the toluene disproportionation was an order of magnitudeslower than transalkylation reactions. An addition of 5–10 wt.% TeMBs to the heavy reformate causedminor impact on the xylene yield but an improvement in xylene selectivity.