Catalysis by Transition-Metal Carbides. VII. Kinetic and XPS Studies of the Decomposition of Methanol on TiC, TaC, Mo2C, WC, and W2C

Abstract

The catalytic decomposition of methanol was investigated on a series of powdered transition-metal carbides, such as TiC, TaC, Mo2C, WC, and W2C, which had been catalytically activated by evacuation at high temperatures. WC was found to produce methyl formate (HCOOCH3) with a high selectivity (above 80%), whereas CO and H2 were mainly produced on clean TaC, Mo2C, and W2C surfaces. XPS measurements combined with an analysis of the peak intensities revealed that the catalytic activation of WC and TaC was attributable to the removal of surface oxygen and the subsequent formation of monocarbide surfaces. On the other hand, the minor activities leading to the formation of methyl formate on W2C and Mo2C were concluded to be due to the formation of oxycarbide surfaces. The deuterium distributions in the products during the reaction of CH3OD suggest that the methyl formate is produced via the dimerization of the intermediate adspecies, CH2O.

First-Principles Study of TiN/MgO Interfaces

“…Technologically, such materials have attracted attention as highly stable field electron emitters [2][3][4] and catalysts for various surface chemical reactions [5][6][7]. The metal compound TiN is one such material.…”

Density functional theory study into the adsorption of CO2, H and CHx (x=0–3) as well as C2H4 on α-Mo2C(0001)

“…It has been demonstrated that transition metal carbides have excellent catalytic activity in a wide variety of hydrogen-involved reactions [2][3][4][5][6][7][8][9][10][11], such as hydrocarbon synthesis from CO hydrogenation [3,[12][13][14][15], dehalogenation [8], hydrodesulfurization [16,17] and hydrodenitrogenation [18,19]. CH 4 dry reforming has received high attention, because it can convert these cheapest carbon containing materials into useful chemical products (CH 4 + CO 2 = 2CO + 2H 2 ).…”

Surface structure and energetics of oxygen and CO adsorption on α-Mo2C(0001)

“…Considerable attention has been focused in recent years on the chemical and physical properties of late transition metal carbides (TMC) because of their excellent catalytic properties that resemble group VIII metals in many hydrogeninvolved reactions [1][2][3][4][5][6][7][8][9]. In particular, they also have an interesting combination of useful properties such as extreme hardness, high melting point and metallic conductivity [10].…”