Catalytic Properties Of Supported Nano-palladium Catalyst For Alkadienes And Acetylene Selective Hydrogenation

Alkadienes and acetylene selective hydrogenation are important process for petrochemical industry and fine chemistry industry. The catalytic reaction properties of long-chain alkadienes selective hydrogenation over nano-palladium supported on nano-titania catalysts had been studied by using micro-reactor tests and industrial sideline tests combined with X-ray diffraction (XRD), special surface area and pore framework measurements, CO chemical adsorption, thermogravimetry and differential thermal analysis (TG-DTA). The specific influence of the molding techniche of nano Pd/TiO2 catalyst, the pore structure of support, the geometric shape of catalyst and the distribution of palladium on the molded TiO2 support on the long-chain alkadienes selective hydrogenation was researched systematically and profoundly. The catalytic properties of acetylene selective hydrogenation over nano-palladium catalyst supported on carbon nanobubes (CNTs) had been investigated. The detailed finding would provide reference information to the research and development of novel useful nano-catalysts for alkadienes and acetylene selective hydrogenation:The main contents of this dissertation are summarized as follows:1. A new molding approach of supported nano Pd/TiO2 catalyst was invented. Pd/TiO2 powder catalyst was prepared first then it was kneaded and extruded with Al2O3 as binder. The heat treatment through molding process was taken under nitrogen gas protection. This Pd/TiO2 catalyst satisfies the industry application demands because it not only had well mechanical intensity, but also performed well for alkadienes selective hydrogenation. The influence of different pore forming materials on the molded nano-TiO2 support pore structure and the catalytic reaction properties of long-chain alkadienes selective hydrogenation over Pd/TiO2 catalyst had been researched systematically. It was found tha the Pd catalyst loaded on molded TiO2 carrier which taken aluminum stearate as pore former had better properties of long-chain alkadienes selective hydrogenation.2. The geometric shape of moled TiO2 support and the distribution of palladium on the molded TiO2 support were of importance for the catalytic reaction property of alkadienes selective hydrogenation. The palladium catalyst loaded on the trefoil TlO2 support was in favor of increasing alkenes selectivity. And the egg-shell type palladium catalyst had better alkenes selectivity than the catalyst that palladium component distributed evenly.3. The method for preparing trefoil molded TiO2 support without Al2O3 as binder was investigated. The industrial sideline tests result of alkadienes selective hydrogenation reaction over palladium catalyst supported on pure molded TiO2 support showed that the catalytic properties of long-chain alkadienes selective hydrogenation were well and performed stably.4. The distribution of nano-palladium catalyst taking carbon nanotubes as support and the pore diameter of CNTs had important influence on the properties of acetylene selective hydrogenation. The ethylene selectivity of Pd/CNTs (out) catalyst was higher than Pd/CNTs (in) catalyst probably because palladium particles on the CNTs outer surface could obtain more charge from CNTs support. For Pd/CNTs (out) catalyst, the acetylene conversion decreased when the pore diameter of CNTs decreased because the electron density of CNTs outer surface with smaller diameter was higher.