Xiaoqiao Zhang,Jianhong Gong,Xiaoli Wei,Lingtao Liu
In this study, a sequential reaction using selected metal oxides, followed by ZSM-5-based catalysts, was employed to demonstrate a promising route for enhancing light olefin production in the catalytic cracking of naphtha. The rationale for the reaction is based on the induction of alkenes into hydrocarbon feeds prior to cracking. The optimum olefin induction was achieved by carefully optimizing the dehydrogenation active sites Mo/Al2O3catalyst. The formed alkenes have a lower activation energy for C-H/C-C bond breaking compared to alkanes. This could accelerate the formation of carbenium ions, thus promoting the conversion of n-octane to produce light olefins. Detailed product distribution and DFT calculation indicated a remarkable increase in ethylene and propylene production in the final product through a modified reaction pathway. Compared with the common metal-promoted zeolite catalysts, the new route could avoid the block of zeolite channels and corresponding decreased catalytic cracking activity. The feasibility of the proposed route was confirmed with different ratios of dehydrogenation catalyst to the reactant. The highest yields of ethylene and propylene reached 13.22% and 33.12% with ratios of Mo/Al2O3and ZSM-5-based catalyst ton-octane both 10:1 at 600 °C. Stability tests showed that the catalytic activity of the double-bed system was stable over 10 cycles.Keywords:naphtha;dehydrogenation;cracking;DFT calculation;synergetic effect
Yong-Rui Pi,Jun Tan,Hui Liu,Jie Chen,Zhu-You Qun,Yan-Bo Zeng,Lei Li
Catalytic cracking reaction of 1,2-dimethyl-1,1,2,2-tetrachlorodisilane with a halobenzene (PhCl, PhBr) to prepare methylphenyldichlorosilane has been investigated. Pd(PPh3)4 exhibited the best catalytic activity among the catalysts used. The activity of chlorobenzene was significantly lower than that of bromobenzene. With the latter and toluene as solvent, in the presence of 0.3 mol % Pd(PPh3)4, the conversion of disilane was 100% with a selectivity to MePhSiCl2 of 97.1%.
Graphical Y/ZSM-5 composite zeolite was synthesized by an aerosol-assisted hydrothermal method including a two-step crystallization. The structure and acidity of the composite zeolite can be modulated by monitoring the synthesis conditions. Y/ZSM-5 composite zeolite was synthesized by an aerosol assisted hydrothermal method including a two-step crystallization. The aerosol technique was used to prepare the precursor of Y/ZSM-5 composite zeolite. This helped to fully utilize the amorphous silica-alumina species left in the primary crystallization solution of NaY zeolite, and to bring the two zeolites close to each other during the second crystallization step. The optimal adding sequence and synthesis conditions were investigated to reduce the amount of template and accelerate the crystallization rate. The composite zeolites were analyzed using XRD, SEM, nitrogen physical adsorption, NH 3 -TPD techniques. It was found that the acid properties can be adjusted by modulating the SiO 2 /Al 2 O 3 molar ratio of the secondary crystallization feed. The BET specific surface area of the optimal Y/ZSM-5(20) composite zeolite is 502 m 2 /g, the pyrolysis conversion rate of 1,3,5-triisopropylbenzene reaches 95.1 %, and the selectivity to benzene reaches 53.4 %.
危险品化学品经营许可证（带存储）