Hydrocarbon aromatization catalysts

Life Testing of Light Hydrocarbon Aromatization Catalysts... 

From elution chromatography, the percentage of aliphatic hydrocarbons, aromatic hydrocarbons and polar compounds were obtained. The percentage of polar compounds in the oil decreased as the catalyst concentration increased (see Figure 1) with mainly an increase in the percentage of aromatic hydrocarbons. There was also a decrease in the percentage of both acids and bases in the oil as the catalyst concentration increases as shown in Figure 1. 

A mixture of CO + H2 is used in the Fischer-Tropsch reaction to make hydrocarbons in high yields. The reaction requires a catalyst, usually Fe or Ni supported on silica, a temperatue of 200-400°C and a short contact time. Depending on the conditions, aliphatic hydrocarbons, aromatic hydrocarbons, alcohols, and acids can be produced. If NH3 is added to the CO + H2, then amino acids, purines, and pyrimidines can be formed.23 The intermediates in these reactions are not known, but it is likely that HCN is involved together with some of the intermediates postulated for the electric discharge processes. 

Homoaerothionin, biosynthesis of 1315, 1316 HomocaUxarenes, synthesis of 1376-1381 Homoerysodienones, formation of 1297 B-Homoerythrina alkaloids 1297 synthesis of 1300 Honey, analysis of 961, 973 Horseradish peroxidase 974, 977, 978, 981 as oxidation catalyst 1216, 1217, 1219-1221, 1224, 1225 HPLC, normal phase 953 H-point standard additions method 954 HSZ-360 catalyst 680 Hydrocarbons, aromatic,... 

The first practical application of these studies was obtained by Zelinsky (/), Shuikin (S), and their collaborators by developing a platimun-charcoal catalyst which was able to dehydrogenate the six carbon ring cyclanes, present in narrow boiling gasoUne fractions, to corresponding aromatic hydrocarbons. The catalyst was active for three months without regeneration. 

Methenylation of aromatic hydrocarbons without catalysts was discussed in Section 8.4. 

Figure 1 shows the yields of conversion and the products distribution (Cj Cg hydrocarbons, aromatic, polyaroioatics and tar) as a function of reactor temperature for pure cyclopentanone over Il-ZSM-5/bentonite (80/20 Wt.%) catalyst. The conversion is completed at 350 C. The main reaction is a ther.nal decarbonylation of cyclopentanone, giving hydrocarbon fragment that reacts further on the catalytic bed to produce aliphatic, aromatic and polyaroiaatic hydrocarbons. Cyclopentenone which is partially deoxygenated (32%) over H-ZSM-5/bentonite (80/20 Wt.%) at 450 C, can be completely converted... 

H-ZSM-5 is also used as catalyst in the large-scale MTG (methanol to gasoline) process. The products are hydrocarbons, aromatics in the benzene range, and water. The reaction is based on the dehydration of methanol to dimethyl ether, followed by numerous reactions that proceed via carbenium ion intermediates. The largest molecules observed, e.g., durene (1,2,4,5-tetramethylbenzene), correspond to the high-boiling components of gasoline. The favorable product distribution in this process can be attributed to restricted transition state selectivity. 

The introduction of one of the halogens onto the aromatic ring is an important synthetic procedure. Chlorine and bromine are reactive toward aromatic hydrocarbons, although catalysts are often needed to achieve desirable rates. Fluorine reacts too violently to be controlled. Iodine can effect substitution of only very reactive aromatic compounds, but synthetic methods involving oxidants for direct introduction of iodine into less reactive molecules have been developed. 

Uses Catalyst for olefin polymerization, aromatic hydrogenation catalyst component in linear oligomerization and cyclization of unsat. hydrocarbons rubber catalyst component intermediate in alkylation reactions... 

Lead has been used as a moderating agent in bimetallic and trime-tallic hydrocarbon reforming catalysts. In the latter case, lead is deposited on a Pt-Re-alumina support, decreasing its acidity, and this modifies both the catalyst stability and selectivity in the reforming of heptane, giving increased selectivity to aromatics and C7 isomers with decreased formation of low hydrocarbons. 

The two-component organometallic catalyst MeTiClj—MeAlCU [90,91 [, which is distinct from other Ti-Al systems, shows the following order of activity for the dimerization of ethylene in organic solvents chlorinated hydrocarbons > aromatic hydrocarbons > aliphatic hydrocarbons. It exists as the following struc-mral formulas ... 

Hierarchical (or mesoporous) zeolites became the focus of the review by Christensen et al. [7]. The main reason behind the development of hierarchical zeolites is to achieve heterogeneous catalysts with an improved porous structure and thereby enhanced performance in alkylation of benzene with alkenes, alkylation, and acylation of other compounds, methanol conversion into hydrocarbons, aromatization processes, isomerization of paraffins, cracking of diverse substrates and raw materials (naphtha, aromatic compounds, hexadecane, vacuum gas oil, and some polymers), and hydrotreating. The reactions that are of interest from the point of view of fine chemicals synthesis occurring on hierarchical zeohtes include aldol condensation, esterification, acetalization, olefin epoxidation, and Beckmarm rearrangement. 

By passing a mixture of carbon monoxide and hydrogen chloride into the aromatic hydrocarbon in the presence of a mixture of cuprous chloride and aluminium chloride which acts as a catalyst (Gattermann - Koch reaction). The mixture of gases probably reacts as the equivalent of the unisolated acid chloride of formic acid (formyl chloride) ... 

The high acidity of superacids makes them extremely effective pro-tonating agents and catalysts. They also can activate a wide variety of extremely weakly basic compounds (nucleophiles) that previously could not be considered reactive in any practical way. Superacids such as fluoroantimonic or magic acid are capable of protonating not only TT-donor systems (aromatics, olefins, and acetylenes) but also what are called (T-donors, such as saturated hydrocarbons, including methane (CH4), the simplest parent saturated hydrocarbon. 

The classification of hydrocarbons as aliphatic or aromatic took place m the 1860s when It was already apparent that there was something special about benzene toluene and their derivatives Their molecular formulas (benzene is CgHg toluene is C7Hj ) indicate that like alkenes and alkynes they are unsaturated and should undergo addition reac tions Under conditions m which bromine for example reacts rapidly with alkenes and alkynes however benzene proved to be inert Benzene does react with Bi2 m the pres ence of iron(III) bromide as a catalyst but even then addition isn t observed Substitu tion occurs instead ... 

With Friedel-Crafts catalysts, butyrolactone reacts with aromatic hydrocarbons. With ben2ene, depending on experimental conditions, either phenylbutyric acid or 1-tetralone can be prepared (162). 

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