The direct carbonylation of methanol, without any halide in the feed as apromoter, is presented. A series of Mo catalysts supported on activated carbon, γ-Al_2O_3 and SiO_2were prepared. The results show that the support greatly affects the Mo catalyst in the directvapor-phase carbonylation of methanol, and activated carbon is the best supports of the investigatedsupports. In addition, the relationships between adsorptions of NH_3 and CO and carbonylation ofmethanol were investigated. A novel sulfided Mo/C catalyst had high activity and selectivity for thevapor phase carbonylation of methanol to methyl acetate without the addition of a CH_3I promoter tothe feed. The reaction conditions were optimized at a reaction temperature of 573 K, a methanolconcentration of 23 mol% and a carbon monoxide space velocity of 3,000 L/(kg·h). Under theseoptimal conditions a methanol conversion of 50%, carbonylation selectivity of 80 rnol%, andspace-time yield of 8.0 mol/(kg·h) were obtained. The active phase of this novel sulfided Mo/Ccatalyst is the non-crystalline phase, and the active component is present as MoS_(2.5) on thesurface of the activated carbon.
Feng PengDepartment of Chemical Engineering, South China University of Technology, Guangzhou 510640, China
The nanocarbonaceous material with helical structure is considered to be promising as nanocoils. Both left and right handed helical structures normally coexist and are disordered. So far, there has been no report about double or multi directional helical structures on an individual nanomaterial. In this paper, Multi directional helical structures were observed in an individual carbon nanofiber during the pyrolysis of acetylene at a mixture of C2H2∶ H2=2∶ 1. It is possible to control and prepare multi directional helical nanomaterial, and it can be used into new application area.
