Xylene from methane

Neopentane does not undergo isomerization 185) on chromia/alumina (non-acidic) at 537°C, the only significant reaction been hydrogenolysis to methane and iso-C4. However, the reality of isomerization is made clear from, for instance, the formation of xylenes from 2,3,4-trimethylpentane. For o- and p-xylene, the reactions are (24) and (25) 182, 93). These processes are formally quite analogous to those we have described in previous... 

Amm oxida tion, a vapor-phase reaction of hydrocarbon with ammonia and oxygen (air) (eq. 2), can be used to produce hydrogen cyanide (HCN), acrylonitrile, acetonitrile (as a by-product of acrylonitrile manufacture), methacrylonitrile, hen onitrile, and toluinitnles from methane, propylene, butylene, toluene, and xylenes, respectively (4). 

It is convenient to divide the petrochemical industry into two general sectors (/) olefins and (2) aromatics and their respective derivatives. Olefins ate straight- or branched-chain unsaturated hydrocarbons, the most important being ethylene (qv), [74-85-1] propjiene (qv) [115-07-17, and butadiene (qv) [106-99-0J. Aromatics are cycHc unsaturated hydrocarbons, the most important being benzene (qv) [71-43-2] toluene (qv) [108-88-3] p- s.y en.e [106-42-3] and (9-xylene [95-47-5] (see Xylenes and ethylbenzene) There are two other large-volume petrochemicals that do not fall easily into either of these two categories ammonia (qv) [7664-41-7] and methanol (qv) [67-56-1]. These two products ate derived primarily from methane [74-82-8] (natural gas) (see Hydrocarbons, c -c ). 

The meta-selectivity for toluene activation, observed for both systems, is very unusual (Fig. 5). Also remarkable is the switch in selectivity from aryl C-H activation to benzylic activation inp-xylene, just by changing the chelate ligand from the diimine equipped with trifluoromethyl substitutents in the meta-positions of the phenyl residue to the diimine bearing methyl substituents in the ortho-positions (Fig. 5). The authors suggested that the C-H bond activation is reversible and the isomeric a-methane complexes are in equilibrium prior to the substitution of... 

Now for an explanation of the hydrogenolytic behavior of phenylaryl-methane, in which only one benzene ring has methyl groups. In the reaction of 4-MeDPM, the molar ratio of toluene and p-xylene was found to be 3.56 1 from the distribution of the reaction products. From this ratio it... 

Sulfuric acid is number 1 by far, with a volume of over 90 billion lb produced yearly in the U.S. It is way ahead of number 2, nitrogen, which is produced at more than 75 billion lb annually. The highest volume organic chemical is ethylene, the basic petrochemical used to synthesize so many other important organic chemicals. It is the leader of the basic seven organics—ethylene, propylene, the C4 mixture, benzene, toluene, xylene, and methane—from which all other important organic chemicals are derived. Methane does not itself appear in the list because it is not synthesized by a chemical process. However, it is the major constituent in natural gas and is used to make many other chemicals. 

The olefins—ethylene, propylene, and the butylenes—are derived from natural gas and petroleum. Methane is the major constituent in natural gas. The aromatics— benzene, toluene, and the xylenes— are derived from petroleum. About 90% by weight of the organic chemicals in the world comes from natural gas and petroleum. But actually only 3% of this crude oil and 6% of refinery output in the U.S. is processed into chemicals, with the rest going as various fuels. Although we are a small user of the petroleum industry, this 3-6% going to petrochemical feedstock is important to us ... 

A relatively small number of chemicals form the basis of the petrochemical industry. These are methane, ethylene, propylene, butylenes, benzene, toluene, and xylenes. These chemicals are used to derive thousands of other chemicals that are used to produce countless products. Figure 19.2 lists some of the principal chemicals and products derived from these seven basic chemicals. 

Product distribution data (Table V) obtained in the hydrocracking of coal, coal oil, anthracene and phenanthrene over a physically mixed NIS-H-zeolon catalyst indicated similarities and differences between the products of coal and coal oil on the one hand and anthracene and phenanthrene on the other hand. There were differences in the conversions which varied in the order coal> anthracene>phenanthrene coal oil. The yield of alkylbenzenes also varied in the order anthracene >phenanthrene>coal oil >coal under the conditions used. The alkylbenzenes and C -C hydrocarbon products from anthracene were similar to the products of phenanthrene. The most predominant component of alkylbenzenes was toluene and xylenes were produced in very small quantities. Methane was the most and butanes the least predominant components of the gaseous product. The products of coal and coal oil were also found to be similar. The most predominant components of alkylbenzenes and gaseous product were benzene and propane respectively. The data also indicated distinct differences between products of coal origin and pure aromatic hydrocarbons. The alkyl-benzene products of coal and coal oil contained more benzene and xylenes and less toluene, ethylbenzene and higher benzenes when compared to the products from anthracene and phenanthrene. The gaseous products of coal and coal oil contained more propane and butanes and less methane and ethane when compared to the products of anthracene and phenanthrene. The differences in the hydrocracked products were obviously due to the differences in the nature of reactants. Coal and coal oil contain hydroaromatic, naphthenic, heterocyclic and aliphatic structures, in addition to polynuclear aromatic structures. Hydrocracking under severe conditions yielded more BTX as shown in Table VI. The yields of BTX obtained from coal, coal oil, anthracene and phenanthrene were respectively 18.5, 25.5, 36.0, and 32.5 percent. Benzene was the most... 

Further Reduction to a Hydrocarbon. In the reduction of benzo-phenone with aluminum ethoxide the formation of 7% of diphenyl-methane was observed. When benzohydrol was treated with aluminum ethoxide under the same conditions, 28% reduction to diphenylmethane occurred.12 In these reactions acetic acid, rather than acetaldehyde,-was formed from the ethoxide. Aluminum isopropoxide does not give this type of undesirable reaction with this reagent, pure benzohydrol is easily obtained in 100% yield from benzophenone.6 37 However, one case of reduction of a ketone to the hydrocarbon has been observed with aluminum isopropoxide.17 When 9, 9-dimethylanthrone-10 (XU) was reduced in xylene solution, rather than in isopropyl alcohol, to avoid formation of the ether (see p. 190), the hydrocarbon XUII was formed in 65% yield. The reduction in either xylene or isopropyl alcohol was very slow, requiring two days for completion. 

HDA [HydroDeAlkylation] A proprietary dealkylation process for making benzene from toluene, xylenes, pyrolysis naphtha, and other petroleum refinery intermediates. The catalyst, typically chromium oxide or molybdenum oxide, together with hydrogen gas, removes the methyl groups from the aromatic hydrocarbons, converting them to methane. The process also converts cresols to phenol. Developed by Hydrocarbon Research with Atlantic Richfield Corporation and widely licensed worldwide. 

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