Dehydrogenation coupling of methane

Yamaguchi J, Saito C. Selective synthesis of ethylene by dehydrogenative coupling of methane by use of thermal diffusion column. Bull Chem Soc Jpn 1989 61 2649-50. 

Gesser HD, Morton LA. The dehydrogenative coupling of methane to form higher hydrocarbons in a hot wire thermal diffusion column. Catal Lett 1991 11 357—63. 

Although ethylene is produced by various methods as follows, only a few are commercially proven thermal cracking of hydrocarbons, catalytic pyrolysis, membrane dehydrogenation of ethane, oxydehydrogenation of ethane, oxidative coupling of methane, methanol to ethylene, dehydration of ethanol, ethylene from coal, disproportionation of propylene, and ethylene as a by-product. 

Selective oxidations, e.g., propane to acroleine, butane to maleic anhydride, ethylene to ethylene oxide Oxidative dehydrogenations of hydrocarbons Oxidative coupling of methane Methane oxidation to syngas... 

Lanthanum oxide is well-known as an active isomerization (406) and hydrogenation catalyst (407), and it has attracted much attention recently (along with other basic oxides, such as MgO and CaO) as a catalyst for the oxidative dehydrogenation and coupling of methane to C2 hydrocarbons (408-410). Its activity for selective NO reduction of CH4 in excess oxygen has also been demonstrated (411, 412). 

Several profound theoretical and experimental studies performed on the laboratory scale have been reported which focus on the use of various configurations of membrane reactors as a reactant distributor in order to improve selectivity-conversion performances. In particular, several industrially relevant partial oxidations have been investigated, including the oxidative coupling of methane [56], the oxidative dehydrogenations of propane [57], butane [58], methanol [59, 60], the epoxidation of ethylene [61], and the oxidation of butane to maleic anhydride [62]. 

Niobium oxide (niobia) is an active catalyst, and can be used as a support for metal nanoparticles or oxides, and it can serve as a promoter in some reactions ([43 5] and references therein). Catalytic applications of niobia include the Fischer-Tropsch synthesis, oxidative dehydrogenation of alkanes, and oxidative coupling of methane. Studies on high-surface-area niobium oxides are complicated by a high degree of complexity because several stable structures (NbO, NbO and Nb O ) exist and the resulting surfaces of high-surface-area niobium oxides are not simple truncations of bulk niobia structures. This is even more so for supported metal oxides when two-dimensional thin films of niobium oxide partially cover a support oxide (Al Oj, SiOj, ZrOj, TiOj, [43]). Nb Oj was also used as a support for V, Cr, Re, Mo, and W oxide overlayers [45, 46]. 

In addition to the systems listed in Table I for the oxidative dehydrogenation of ethane, other systems have been tested because they have proven to be active in other alkane oxidations this is particularly the case of many catalysts used in the oxidative coupling of methane, VPO and magnesium phosphate catalysts (butane oxidation and propane dehydrogenation, respectively) and MoVO catalysts. Various zeolites have also been tested. This table, the largest to be presented here, perfectly illustrates the fact that no formulation seems convincingly better than the others. 

To promote both the conversion of reactants and the selectivity to partial oxidation products, many kinds of metal compounds are used to create catalytically active sites in different oxidation reaction processes [4]. The most well-known oxidation of lower alkanes is the selective oxidation of n-butane to maleic anhydride, which has been successfully demonstrated using crystalline V-P-O complex oxide catalysts [5] and the process has been commercialized. The selective conversions of methane to methanol, formaldehyde, and higher hydrocarbons (by oxidative coupling of methane [OCM]) are also widely investigated [6-8]. The oxidative dehydrogenation of ethane has also received attention [9,10],... 

Examples Oxidative coupling of methane (OCM), oxidative dehydrogenation of C -C4 alkanes, partial oxidation of methane to synthesis gasa, combined oxidative coupling of methane and toluene to styrene Surface-stabilized combustion, partial oxidation of methane to synthesis gasa, synthesis of cyanic acid from methane, ammonia, and oxygen3... 

The reaction mechanisms for thermal coupling of methane has been studied by various researchers [175], The overall reaction in thermal coupling of methane can be described as a stepwise dehydrogenation at high temperature. 

Tables 27.2 (for hydrogen production), 213 (for the oxidative coupling of methane) and 27.4 (for the oxidative dehydrogenation of alkanes).

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