Hydroisomerization products

There are currentiy three important processes for the production of isobutylene (/) the extraction process using an acid to separate isobutylene (2) the dehydration of tert-huty alcohol, formed in the Arco s Oxirane process and (3) the cracking of MTBE. The expected demand for MTBE wHl preclude the third route for isobutylene production. Since MTBE is likely to replace tert-huty alcohol as a gasoline additive, the second route could become an important source for isobutylene. Nevertheless, its avaHabHity wHl be limited by the demand for propylene oxide, since it is only a coproduct. An alternative process is emerging that consists of catalyticaHy hydroisomerizing 1-butene to 2-butenes (82). In this process, trace quantities of butadienes are also hydrogenated to yield feedstocks rich in isobutylene which can then be easHy separated from 2-butenes by simple distHlation. 

Shell Gas B.V. has constructed a 1987 mVd (12,500 bbhd) Fischer-Tropsch plant in Malaysia, start-up occurring in 1994. The Shell Middle Distillate Synthesis (SMDS) process, as it is called, uses natural gas as the feedstock to fixed-bed reactors containing cobalt-based cat- yst. The heavy hydrocarbons from the Fischer-Tropsch reactors are converted to distillate fuels by hydrocracking and hydroisomerization. The quality of the products is very high, the diesel fuel having a cetane number in excess of 75. 

The hydroisomerization of heavy linear alkanes is of a great interest in petroleum industry. Indeed, the transformation of long chain n-alkanes into branched alkanes allows to improve the low temperature performances of diesel or lubricating oils [1-3]. On bifunctional Pt-exchanged zeolite catalysts, n-CK, transformed into monobranched isomers, multibranched isomers and cracking products [4], The HBEA zeolite based catalyst was more selective for isomerization than those containing MCM-22 or HZSM-5 zeolites [4], This was explained on one hand by a rapid diffusion of the reaction intermediates inside the large HBEA channels, and on the other hand by the very small crystallites size of this zeolite (0.02 pm). 

The development of composite micro/mesoporous materials opens new perspectives for the improvement of zeolytic catalysts. These materials combine the advantages of both zeolites and mesoporous molecular sieves, in particular, strong acidity, high thermal and hydrothermal stability and improved diffusivity of bulky molecules due to reduction of the intracrystalline diffusion path length, resulting from creation of secondary mesoporous structure. It can be expected that the creation of secondary mesoporous structure in zeolitic crystals, on the one hand, will result in the improvement of the effectiveness factor in hydroisomerization process and, on the other hand, will lead to the decrease of the residence time of products and minimization of secondary reactions, such as cracking. This will result in an increase of both the conversion and the selectivity to isomerization products. 

The co-refining synergy of natural gas liquids and Fe-HTFT was exploited for alkylate production. The natural gas liquids serve as a source of butane that can be hydroisomerized to yield isobutane that is alkylated (HF process) to produce a... 

Soualah, A., Lemberton, J.L., Pinard, L., Chater, M., Magnoux, P., and Moljord, K. (2008) Hydroisomerization of long-chain n-alkanes on bifunctional Pt/zeolite catalysts effect of the zeolite strucmre on the product selectivity and on the reaction mechanism. Appl. Catal. A., 336, 23-28. 

BRANCHING ANALYSIS OF HYDROGENATED PLATFORMING PRODUCTS OBTAINED BY HYDROISOMERIZATION OF PARAFFIN WAX... 

A more detailed picture of hydroisomerization of n-octane and n-nonane is given in Table II in which product distributions are listed for different degrees of conversion along with thermodynamic equilibrium values. The latter have been calculated from Gibbs free energy data available in literature (F7) the accuracy of which, however, is not known. From Table II the following conclusions may be drawn ... 

Hydroisomerization proceeds towards thermodynamic equilibrium which is approximately reached between the normal, mono-branched and di-branched structures at high degrees of overall conversion. Hydrocracking, however, is severe under these conditions. It is evident from Table II that monomethyl isomers are primary products the same is apparently true for monoethyl isomers although due to thermodynamic reasons lower concentrations are obtained. Dimethyl isomers including those containing a quarternary carbon atom are formed as secondary products. However, trimethyl isomers are formed very slowly so that their concentrations do not reach equilibrium values. It follows from this that the number of ramifications is deciding as to whether a branched isomer is a primary, secondary or tertiary product in hydroisomerization of n-octane and n-nonane. 

According to the reaction scheme shown in Figure 5 both hydroisomerization and hydrocracking of the n-alkanes (except n-hexane) proceed via branched alkyl carbenium ions. In the range of medium degrees of conversion (40 % <,X <, 90 %) both reactions may be investigated simultaneously. A relationship between the products of both types of reaction will be discussed in the present section. 

The values defined in this manner do not represent any probability for rupture of definite carbon-carbon bonds in the feed molecule. This term is meaningless if rearrangement of the carbon skeleton precedes the cracking step. Rather, the values indicate the probability of an n-alkane for being hydrocracked according to the overall cracking reaction in question. These probabilities are useful for a comparison with the relative concentrations of the products formed by hydroisomerization (cf. Table IV). 

Hydrogenolysis has been concluded in a preceeding section to be mainly responsible for the formation of + Cm 1 and Cg + Cm 2 Branching in the fractions p = m-1 and p = m-2, then, may be due to hydroisomerization of either the feed or the cracked products according to the reaction sequences ... 

Description Crude C4 streams are converted into propylene and an isobutylene-rich stream in three IFP process steps (1) butadiene and C4 acetylenes selective hydrogenation and butenes hydroisomerization, (2) isobutylene removal via distillation or MTBE production and (3) metathesis (Meta-4). 

The hydroisomerization step features complete C4 acetylenes and butadiene conversion to butenes, maximum 2-butenes production, flexibility to process different feeds, polymer-free product and no residual hydrogen. The second step separates isobutylene either by conventional distillation, or by reacting the isobutylene with methanol to produce MTBE. 

Application Increase the value of steam cracker C4 cuts via low-temperature selective hydrogenation and hydroisomerization catalysis. Several options exist removal of ethyl and vinyl acetylenes to facilitate butadiene extraction processing downstream conversion of 1, 3 butadiene to maximize 1-butene or 2-butene production production of high-purity isobutylene from crude C4 cuts total C4 cut hydrogenation and total hydrogenation of combined C3/C4 and C4C5 cuts for recycle to cracking furnaces or LPG production. 

MWI [Mobil Wax Isomerization] A process for improving the quality of petroleum-based lubricating oils. The undesirable wax constituents are hydroisomerized to products of lower molecular weight, using a zeolite catalyst, and the resulting product is treated with an organic peroxide to increase its viscosity. Developed by Mobil Oil Corporation in 1990. 

The latest industrial application of metathesis was developed by Phillips who started up a plant in late 1985 at Cbannelview, Texas, on the L ondell Petrochemical Complex with a production capacity of 135,000 t/year of propylene from ethylene. This facility carries out the disproportionation of ethylene and 2-butenes, in the vapor phase, around 300 to 350°C, at about 0.5.10 Pa absolute, with a VHSV of 50 to 200 and a once-througb conversion of about 15 per cent 2-butenes are themselves obtained by the dimerization of ethylene in a homogeneous phase, which may be followed by a hydroisomerization step to convert the 1-butene formed (see Sections 13.3.2. A and B). IFP is also developing a liquid phase process in this area. 

Although FT waxes are high in quality, their availability over the next decade is expected to be limited. Therefore, there is an effort to find other sources of feedstocks of equal quality to co-process along with FT waxes, both to meet the demand and decrease the cost of lubricant products. Waste plastic is a potentially significant new source for such waxy feed. We have performed combined pyrolysis-hydroisomerization experiments, looking at the following feedstock options ... 

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