A low temperature reaction sequence for methane conversion

Abstract

Surface carbonaceous intermediates produced from methane are shown to produce small alkanes upon hydrogenation below 400 K.Current practice to convert natural gas to higher hydrocarbons proceeds by the indirect route in which natural gas is first converted to synthesis gas at a high temperature.1 Subsequently, hydrocarbons are produced in a low temperature exothermic process from synthesis gas.2.3 Direct methane conversion, like pyrolysis to acetylene and benzene, can only operate at temperatures above 1200 K. 475 Oxidative coupling of methane to ethylene has been proposed as a promising alternative route6-11 and proceeds at temperatures between 850 and 1200 K.

Production of 11C-labelled n-hexane for use in positron emission imaging

“…It can be seen that promotion of the Ru catalyst with vanadium increased the fraction of carbon which was adsorbed in the reactive C a form. The selectivities for products produced from this C,, fraction are also found to be affected by vanadium promotion: the n-hexane selectivity is seen to pass through a maximum with 0.33 wt.% V. In agreement with previous studies [13], we have All product selectivities were measured during hydrogenation at 110°C.…”

“…During the high temperature adsorption it is generally accepted that three types of surface carbon species are formed, and these are generally referred to as Ca, Ct3 and Cv [11][12][13]. TPR studies of the ~C surface species has shown evidence for the existence of both C,~ and C, with maxima in ~ l CH 4 production at 110°C and 200°C, respectively.…”

Direct conversion of methane under nonoxidative conditions

“…In heterogeneous catalysis, various metals have been discovered that can chemisorb CH 4 at moderate temperatures and that can decompose CH 4 to C and H 2 at higher temperatures. Amariglio and co-workers [5] and van Santen and co-workers [6] independently and almost simultaneously reported a "two-step" process.…”

“…Ichikawa and coworkers found that the formation rates of C 6 3 crystallites, and some of them migrate into the zeolite channels and interact with the Brønsted acid sites. Depending on the zeolite used and the preparation methods, the optimum Mo loading for MDA ranges from 2 to 6%.…”

Reaction Routes for Methane Conversion on Transition Metals at Low Temperature

“…Figure 7 compares the amount of products formed during hydrogenation, after separate methane and propene adsorption and their co-adsorption. Surface carbon from methane alone can be hydrogenated to Cz+ hydrocarbons [48]. However, most of the dissociatively adsorbed methane reacts back towards methane.…”