Surface dealuminated Beta zeolites supported WO3 catalyst and its catalytic performance in tetralin hydrocracking

In this study,selective dealumination of Beta zeolites was performed through partially removing the templating agent in Beta zeolites by calcination and then removing the aluminum on the external surface of Beta zeolites with acid treatment.Hydrocracking catalysts were prepared by loading WO_(3)onto these dealuminated Beta zeolites.It was shown that the surface SiO_(2)/Al_(2)O_(3)of selectively dealuminated Beta zeolites was higher than that of conventionally dealuminated samples for the same bulk SiO_(2)/Al_(2)O_(3),and the hydrogenation activity of the catalyst of the selectively dealuminated Beta zeolites was lower than that of conventionally dealuminated Beta zeolites.The experimental results for tetralin hydrocracking to BTX showed that the catalysts based on the selectively dealuminated Beta zeolites had higher BTX selectivity and lower coke formation rate than that the catalysts based on the conventionally dealuminated Beta zeolites.

Synergistic effect of bimetallic RuPt/TiO_(2) catalyst in methane combustion

Designing metal compounds based on their structure and chemical composition is essential in achieving desirable performance in methane oxidation,because of the synergistic effect between different metal elements.Herein,a bimetallic Ru-Pt catalyst on TiO_(2) support(RuPt-O/TiO_(2)) was prepared by in situ reduction followed by calcination in air.Compared with monometallic catalysts(Ru-O/TiO_(2) and Pt-O/TiO_(2)),the synergistic effect of mixed metals endowed bimetallic catalysts with excellent stability and outstanding performance in methane oxidation,with a reaction rate of 13.9×10^(-5)mol^(-1)_(CH_(4))·g^(-1)_(Ru+Pt)·s^(-1)at 303℃.The varied characterization results revealed that among the bimetallic catalysts,RuO_(2)was epitaxially grown on the TiO_(2) substrate owing to lattice matching between them,and part of the PtO_(x) adhered to the RuO_(2) surface,in addition to a single PtO_(x) nanoparticle with 4 nm in size.Consequently,Pt mainly existed in the form of Pt2+and Pt4+and a small amount of zero valence in the bimetallic catalyst,prompting the adsorption and activation of methane as the first and rate-controlling step for CH_(4) oxidation.More importantly,the RuO_(2) species provided additional oxygen species to facilitate the redox cycle of the PtO_(x) species.This study opens a new route for structurally designing promising catalysts for CH4oxidation.