Hydrodesulfurization hydrocracking

In most applications, the reaction occurs between a dissolved gas and a liquid-phase reactant in the presence of a solid catalyst. In some cases, the liquid is an inert medium and the reaction takes place between the dissolved gases at the solid surface. These reactors have many diverse applications in catalytic processes and are used extensively in the chemical industry. Trickle-bed reactors have been developed by the petroleum industry for hydrodesulfurization, hydrocracking, and hydrotreating of various petroleum fractions of relatively high boiling point. Under reaction conditions, the hydrocarbon feed is frequently a vapor-liquid mixture that reacts at liquid hourly space velocities (LHSV in volume of fresh feed, as liquid/volume of bed, hr) in the... 

The heat effects can also be important in gas-liquid-solid reaction systems. Some reactions, such as hydrodesulfurization, hydrocracking, and coal liquefaction are known to be highly exothermic. No analysis of such reactions in the presence of a significant temperature gradient in the liquid phase is presently available. If the heat of solution is negligible, at steady state the heat balance at the catalyst surface would give... 

The primary nses of trickle bed reactors are for hydrodesulfurization, hydrocracking, and hydrotreating of various high-boiUng petroleum fractions. The direct and capital costs are significantly less for trickle bed operation than for an equivalent hydrodesulfurization unit operating... 

Zn pzt/iotOJULm ndu t/u.2, hydrodesulfurization, hydrocracking of heavy or residual oil-stocks, hydrofinishing or hydrotreating of lubricating oils, demetallization, denitrification of gas-oils, isomerization of cyclopropane and hydrogenation of benzene and of naphthenic lube oil distillate (30, 31, 26, 6, 32). 

Reactors are stationary vessels that are classified as batch, semi-batch, or continuous. Some reactors use mixers to blend the individual components. Reactor design depends on the type of service the reactor will be used in. Some of the reactor processes (among many others) include alkylation, catcracking, hydrodesulfurization, hydrocracking, fluid coking, reforming, polyethylene, and mixed-xylene. Figure 7-14 shows the standard symbols for reactors. 

The gas phase consists of hydrocarbons vaporized by distillation processes and/or formed by cracking or other decomposition of fluids. Sulfur compounds, such as hydrogen sulfide and volatile mercaptans, often present in the gas phase, may be components of the original feed to the unit of interest, e.g. the crude still they may be formed by thermal degradation of disulfides, thiophenes, etc., or they may be the result of various hydrogenation processes such as hydrodesulfurizing, hydrocracking, etc. 

In the two-stage operation, the feed is hydrodesulfurized in the first reactor with partial hydrocracking. Reactor effluent goes to a high-pressure separator to separate the hydrogen-rich gas, which is recycled and mixed with the fresh feed. The liquid portion from the separator is fractionated, and the bottoms of the fractionator are sent to the second stage reactor. 

Gulf HDS A process for hydrorefining and hydrocracking petroleum residues in order to make fuels and feeds for catalytic cracking. Developed by the Gulf Research Development Company. See also hydrodesulfurization. 

Trickle-bed reactors are used in catalytic hydrotreating (reaction with H2) of petroleum fractions to remove sulfur (hydrodesulfurization), nitrogen (hydrodenitrogena-tion), and metals (hydrodemetallization), as well as in catalytic hydrocracking of petroleum fractions, and other catalytic hydrogenation and oxidation processes. An example of the first is the reaction in which a sulfur compound is represented by diben-zothiophene (Ring and Missen, 1989), and a molybdate catalyst, based, for example, on cobalt molybdate, is used ... 

Trickle-bed reactors usually consist of a fixed bed of catalyst particles, contacted by a gas liquid two-phase flow, with co-current downflow as the most common mode of operation. Such reactors are particularly important in the petroleum industry, where they are used primarily for hydrocracking, hydrodesulfurization, and hydrodenitrogenation other commercial applications are found in the petrochemical industry, involving mainly hydrogenation and oxidation of organic compounds. Two important quantities used to characterize a trickle-bed reactor are... 

It is well known that the accessibility of the mesoporous materials would play an important role in catalysis, and catalytic activity depends on the free diffusion of the reactants, intermediates and products [5], Thus, a mesoporous molecular sieve with better mass transport pore would be a more suitable candidate for some industrial catalytic reactions of the largesized hydrocarbons in dehydrogenation, hydrocracking or hydrodesulfurization. 

Catalytic hydrogeneration of benzene (early 1960s) Hydrodesulfurization of heavy fuels, also by hydrocracking... 

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