Shell dehydrogenation process

Naphthene Isomerization. In addition to the paraffin isomerization processes, naphthene isomerization also proved useful during the war in connection with the manufacture of toluene. In the Shell dehydrogenation process for the manufacture of toluene, good yields depend upon increasing the methylcyclohexane content of the feed by isomerization of dimethylcyclopentanes. This process was employed commercially at one refinery in the Midwest and one on the Pacific Coast. 

Most routes to butadiene can be extended to the production of isoprene. These include dehydrogenation in the presence of halogens (Shell Idas process) or with oxygen (Phillips process, second step). 

Much attention in the literature has been devoted to oxidative dehydrogenation processes for n-butane since equilibrium is a serious problem in butadiene manufacture also. However, much of the zest for the economic future of oxidative dehydrogenation was lost when Shells Berre plant, based on iodinative dehydrogenation, was not placed on stream. Whether or not this was caused solely by European butadiene oversupply is speculative, but the net effect is that as yet there is no proved commercial oxidative dehydrogenation process to produce butadiene that could be adapted to propylene. 

Figure 6.6 Manufacture of acetone (1,2 and 3) and butanol (4). The cumene hydroperoxide process (1) and the dehydrogenation of propali-2-ol are more important routes to acetone than the Shell glycerol process (3). The oxo-process for butanol manufacture (4) can be controlled so that butan-l-al is the main product of the hydroformylation of propylene...

Y nanoparticle layers were eovered by a Pd over layer (1-2 nm) and hydrogenated at room temperature and different background pressures (3 x 10 to 5 mbar). It was possible to observe hydrogenation effects both optically and electrically, even with the oxide shells, revealing that these shells do not hinder hydrogenation/dehydrogenation process. In the first step metallic YH2 was formed and in the second step additional H formed YHs- (5 < 1 to 5 1). 

The dehydrogenation of 2-butanol is conducted in a multitube vapor-phase reactor over a zinc oxide (20—23), copper (24—27), or brass (28) catalyst, at temperatures of 250—400°C, and pressures slightly above atmospheric. The reaction is endothermic and heat is suppHed from a heat-transfer fluid on the shell side of the reactor. A typical process flow sheet is shown in Figure 1 (29). Catalyst life is three to five years operating in three to six month cycles between oxidative reactivations (30). Catalyst life is impaired by exposure to water, butene oligomers, and di-j -butyl ether (27). 

Selectivity may also come from reducing the contribution of a side reaction, e.g. the reaction of a labile moiety on a molecule which itself undergoes a reaction. Here, control over the temperature, i.e. the avoidance of hot spots, is the key to increasing selectivity. In this respect, the oxidative dehydrogenation of an undisclosed methanol derivative to the corresponding aldehyde was investigated in the framework of the development of a large-scale chemical production process. A selectivity of 96% at 55% conversion was found for the micro reactor (390 °C), which exceeds the performance of laboratory pan-like (40% 50% 550 °C) and short shell-and-tube (85% 50% 450 °C) reactors [73,110,112,153,154]. 

The naphthene isomerization process has been applied also to the conversion of meth-ylcyclopentane to cyclohexane for subsequent dehydrogenation to benzene. Shell s Wilmington, Calif., refinery has been operating commercial equipment on this basis since March 1950 (18). 

Similar to the processes used in the manufacture of 1,3-butadiene, isoprene can be prepared from isopentane, isoamylenes, or a mixed isoC5 feed.172 176 177 The Shell process177 dehydrogenates isoamylenes to isoprene in the presence of steam with 85% selectivity at 35% conversion, over a Fe203—K2CO3—Cr2Oj catalyst at 600°C. 

Styrene. All commercial processes use the catalytic dehydrogenation of ethylbenzene for the manufacture of styrene.189 A mixture of steam and ethylbenzene is reacted on a catalyst at about 600°C and usually below atmospheric pressure. These operating conditions are chosen to prevent cracking processes. Side reactions are further suppressed by running the reaction at relatively low conversion levels (50-70%) to obtain styrene yields about 90%. The preferred catalyst is iron oxide and chromia promoted with KzO, the so-called Shell 015 catalyst.190... 

Traditionally, ethanol has been made from ethylene by sulfation followed by hydrolysis of the ethyl sulfate so produced. This type of process has the disadvantages of severe corrosion problems, the requirement for sulfuric acid reconcentration, and loss of yield caused by ethyl ether formation. Recently a successful direct catalytic hydration of ethylene has been accomplished on a commercial scale. This process, developed by Veba-Chemie in Germany, uses a fixed bed catalytic reaction system. Although direct hydration plants have been operated by Shell Chemical and Texas Eastman, Veba claims technical and economic superiority because of new catalyst developments. Because of its economic superiority, it is now replacing the sulfuric acid based process and has been licensed to British Petroleum in the United Kingdom, Publicker Industries in the United States, and others. By including ethanol dehydrogenation facilities, Veba claims that acetaldehyde can be produced indirectly from ethylene by this combined process at costs competitive with the catalytic oxidation of ethylene. 

Two types of asphalt were used blown asphalt and emulsified asphalt. Blown asphalt is asphalt stock that has been heated at temperatures from 200°-300°C and had air blown through it. The process is one of dehydrogenation and polymerization, resulting in a product that is thermally more stable. We used a blown asphalt provided by the Exxon Corp. because it most closely resembles Mexphalt R 90/40 (Shell Oil Co.), the blown asphalt used most in Europe. Mexphalt R 90/40 is not available in the U.S., but differs chiefly in being somewhat softer than the asphalt from the Exxon Corp. 

Ethylene for polymerization to the most widely used polymer can be made by the dehydration of ethanol from fermentation (12.1).6 The ethanol used need not be anhydrous. Dehydration of 20% aqueous ethanol over HZSM-5 zeolite gave 76-83% ethylene, 2% ethane, 6.6% propylene, 2% propane, 4% butenes, and 3% /3-butane.7 Presumably, the paraffins could be dehydrogenated catalyti-cally after separation from the olefins.8 Ethylene can be dimerized to 1-butene with a nickel catalyst.9 It can be trimerized to 1-hexene with a chromium catalyst with 95% selectivity at 70% conversion.10 Ethylene is often copolymerized with 1-hexene to produce linear low-density polyethylene. Brookhart and co-workers have developed iron, cobalt, nickel, and palladium dimine catalysts that produce similar branched polyethylene from ethylene alone.11 Mixed higher olefins can be made by reaction of ethylene with triethylaluminum or by the Shell higher olefins process, which employs a nickel phosphine catalyst. 

The value of 2-butanol t ii° = 0 08, >,bpuol3 99.5 C) resides in the fact that 90 per cent of its total production is used for the synthesis of MEK. (methylethyiketone) by dehydrogenation. It is manufactured by the indirect hydration of n-butenes. of which the 1- and 2-isomers yield the same 2-butanoL They are absorbed in 80 per cent weight sulfuric acid, between 15 and 20 C, and 0.7.10 Pa absolute. The salfuric esters obtained are then hydrolysed between 25 and 35°C at 0.1.10 Pa absolute, with 65 to 75 per cent weight sulfuric add (Exxon. Maruzen and Shell processes). Despite considerable research work (Deutsche Texaco. Mitsubishi. Mitsui, Petrotex and Shell), the direct catalytic hydration of H-butenes has not yet reached the industrial stage. 

Normal Paraffin-Based Olefins, Detergent range -paraffins are currently isolated from refinery streams by molecular sieve processes (see ADSORPTION, LIQUID separation) and converted to olefins by two methods. In the process developed by Universal Oil Products and practiced by Enichem and Mitsubishi Petrochemical, a -paraffin of the desired chain length is dehydrogenated using the Pacol process in a catalytic fixed-bed reactor in the presence of excess hydrogen at low pressure and moderately high temperature. The product after adsorptive separation is a linear, random, primarily internal olefin. Shell formedy produced olefins by chlorination—dehydrochlorination. Typically, C —C14 -paraffins are chlorinated in a fluidized bed at 300°C with low conversion (10—15%) to limit dichloroalkane and trichloroalkane formation. Unreacted paraffin is recycled after distillation and the predominant monochloroalkane is dehydrochlorinated at 300°C over a catalyst such as nickel acetate [373-02-4]. The product is a linear, random, primarily internal olefin. 

Another modification of the iodinative-type process for the purpose of reducing I2 usage is a series of Shell patents (see King) that describe the use of a metal oxide or hydroxide acceptor that is capable of reacting with the HI formed during dehydrogenation in the range of 500°C—e.g. 

The dehydrogenation of butenes in the presence of steam was developed initially by Esso, Shell and Phillips. In accordance with the operating principles of this type of process, the preheated feed is mixed with superheated steam and then sent to adiabatic reactors containing catalyst beds 80 to 90 cm thick. The temperature, initially 620 C, must be raised progressively as catalyst activity decreases. The latter is regenerated by simple steam treatment The reaction pressure is 0.1 to 0.2.10A Pa absolute, and reaches 0.5. 1C6 Pa absolute during regeneration. 

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