Luo Bo,Liu Huiyu,Shan Rui,Zhang Jun,Yuan Haoran,Chen Yong
Purpose This work aims to investigate the thermal behavior and kinetic characteristics of polyethylene (PE) pyrolysis over Cu/Ce modified ZSM-5. The influences of metal types, particles size of active center and interaction of Cu–Ce species on products distribution are elucidated. Methods Metal-modified ZSM-5 catalysts were prepared by negative pressure impregnation method. Catalytic fast pyrolysis and thermogravimetric experiments were conducted using Py–GC/MS and TG/MS for the qualitative and quantitative analysis of pyrolysis products. Results Morphology characterization indicated the interaction of Cu–Ce species facilitated the regulation of active center size into a nanoparticle scale. The final products were restricted to a carbon number of less than 9 over CuCe/ZSM-5. Cu–Ce modification increased the aliphatic content from 58.5 to 76.1%. Kinetic analysis revealed a remarkable reduction in activation energies during both the intermediate and final stages, where an average decrease of 30% was achieved. Conclusion The synergistic effects of Cu 0 and CeO x facilitated the formation of more short chain olefins by enhancing C–C bonds cleavage activity. Undesired polycyclic aromatic hydrocarbons (PAHs) were avoided by the optimal steric hindrance of CuCe/ZSM-5. Graphical Abstract
The Cu-Ce modified SAPO-34/ZSM-5 (S-Z) composite molecular sieve catalysts were synthesized via a stepwise crystallization process using triethylamine (TEA) and tetraethylammonium hydroxide (TEAOH) as dual templates. This method significantly reduces the crystallization time from 24 hours to 12 hours. The incorporation of metal ions alters the structure and acid strength of the molecular sieves, thereby decreasing the rate of coke formation during the reaction, which in turn extends the catalyst's lifetime. Experimental results demonstrated that the catalyst's lifetime increased progressively with the addition of Ce. In the methanol-to-olefin reaction, the catalytic lifetime of the S-Z/Cu 0.05 -Ce 0.05 samples reached 1440 mins, approximately 480 mins longer than that of the S-Z samples, while maintaining a selectivity for low-carbon olefins at around 89.6%.
危险品化学品经营许可证（带存储）