Methanol to hydrocarbons conversion

Methanol conversion to hydrocarbons over various zeolites (370X, 1 atm, 1 LHSV)... 

Methanol Conversion to Hydrocarbons. The conversion of methanol to hydrocarbons requires the elimination of oxygen, which can occur in the form of H20, CO, or C02. The reaction is an exothermic process the degree of exothermicity is dependent on product distribution. The stoichiometry for a general case can be written as in Eq. (3.45) ... 

AIPO4 is isoelectronic with silica and, as such, readily forms glasses and Si02-like crystalline materials. As well, framework stmctmes similar to zeolites may be prepared by the use of amines as templates. Like zeolites, these are active in catalytic reactions such as methanol conversion to hydrocarbons (seeZeolites) As a ceramic material, AIPO4 is an infusible material that is insoluble in water but is soluble in alkali hydroxides. It is often used with calcium sulfate and sodium silicate for dental cements. AIPO4 is also used as a white pigment that also acts as a corrosion inhibitor. 

We also studied the effect of ion exchange with on the catalytic activity of acid-treated Bent (H -Bent ), sometimes called activated clay. The results are given in Table IV. H" -Bent is virtually the same as H -Bent in catalytic activity. However, the catalytic activity of Ti -Bent for methanol conversion to hydrocarbons is much higher than that of Ti -Bent. The hydrocarbon yield reaches 90%, and the products, in addition to methane, are primarily olefins lower than Ce. The selectivity for olefin formation is estimated to be 90% or higher based on C2 and C3 hydrocarbon product distribution. Ti -Bent appears to surpass the phosphorus compound-modified zeolite proposed by Kaeding and Butter (31) in selective activity for olefin formation, and has the potential to exceed H-Fe-silicate (32) and Ni-SAPO-34 (33), proposed recently by Inui et al. 

Methanol conversion to hydrocarbons has been studied In a flow micro reactor using a mixture of C-methanol and ordinary C-ethene (from ethanol) or propene (from Isopropanol) over SAPO-34, H-ZSM-5 and dealumlnated mordenlte catalysts In a temperature range extending from 300 to 450 °C. Space velocities (WHSV) ranged from 1 to 30 h. The products were analyzed with a GC-MS Instrument allowing the determination of the Isotopic composition of the reaction products. The Isotope distribution pattern appear to be consistent with a previously proposed carbon pool mechanism, but not with consecutive-type mechanisms. 

On the other hand, it was proposed that acid catalyzed reactions such as skeletal isomerization of paraffin [2], hydrocracking of hydrocarbons [3] or methanol conversion to hydrocarbon [4] over metal supported acid catalysts were promoted by spillover hydrogen (proton) on the acid catalysts. Hydrogen spillover phenomenon from noble metal to other component at room temperature has been reported in many cases [5]. Recently Masai et al. [6] and Steinberg et al. [7] showed that the physical mixtures of protonated zeolite and R/AI2O3 showed high hydrocracking activities of paraffins and skeletal isomerization to some extent. 

Catalytic hydrogenation of CO2 to hydrocarbons is classified into two categories. The one is direct hydrogenation fix)m H2/CO2 to hydrocarbons. The other is indirect process which includes methanol sjmthesis fix>m H2/CO2, followed by in situ methanol conversion to hydrocarbons using sohd acid catalyst in H2/CO2 feed. Study on indirect hydrocarbon synthesis is now popular. 

The overall path of methanol conversion to hydrocarbons over ZSM-5 is illustrated in Fig. 2. Methanol and dimethyl ether (DME) form olefins, which are then converted to naphthenes, aromatics, and paraffins. Olefins initially react by oligomerization and methylation, and at increasing conversion olefins distribution is governed by kinetics. This effect, and the effects of process variables were summarized by Chang (ref. 14). The directional effects of process and catalyst variables on the MTO reaction are summarized in Table 3. 

Spencer and Whittam ° used Fu-1 zeolite to convert methanol to light olefins. NaFu-1 and its H-form are considered to be small-pore zeolites, but they have a high external surface area because of their small crystallite size and plate morphology. Apparently, methanol conversion to hydrocarbons occurs mainly at the interior acid sites, while hydrocarbons can react on both types of acid sites. NaFu-1 showed negligible activity. Using a flow reactor at... 

Dessau worked at very low partial pressures (1-10 Torr) in order to limit olefin reequilibration. At low space times, still under conditions of complete methanol conversion to hydrocarbons. 

Kinetic studies on the methanol conversion to hydrocarbons usually consider the methanol/dimethylether mixture as a single species or "lump". This is justified by the observation that the ether formation is much faster than the subsequent reactions, so that the oxygenates are at equilibrium. Based on the autocatalytic nature of the methanol reaction over ZSM-5, Chen and Reagan used the following simple model, assuming that the rate of disappearance of oxygenates (A) is accelerated by their reaction with olefins (B) ... 

Methanol conversion to hydrocarbons Zeolites Mobil Chemieal Co., 1975... 

Chang CD A kinetic model for methanol conversion to hydrocarbons, Chem Eng Sci 35 619-622, 1980. 

Reaction steps of MeOH conversion into hydrocarbons. Adapted from Chang CD. Hydrocarbons from methanol. Catal Rev Sci Eng 1983 25 1—118 Ceckiewicz S. Methanol conversion to hydrocarbons and dimethyl ether on decationized zeolite-T. Kinet Catal Lett React 1981 16 11. 

Chang CD, Hellring SD, Pearson JA. On the existence and role of Iree radicals in methanol conversion to hydrocarbons over H-ZSM-5 1. Inhibition by NO. J Catal 1989 115 282-5. 

Hunter R, Hutchings GJ, Pickl W. Methanol conversion to hydrocarbons over the zeolite catalyst H-ZSM-5 in the presence of oxygen and nitric-oxide—further evidence against a radical reaction-mechanism. J Chem Soc Chem Commun 1987 1369. 

Hutchings GJ, Johnston P. Methanol conversion to hydrocarbons investigation of the possible role of carbon monoxide in the formation of the initial carbon-carbon bond. Appl Catal 1990 67 L5-9. 

Ceckiewicz S. Methanol conversion to hydrocarbons and dimethyl ether on decationized zeolite-T. Kinet... 

Dessau RM, LaPierre RB. On the mechanism of methanol conversion to hydrocarbons over H-ZSM-5. 

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