Catalysts use in petroleum

Cyclohexane was used as solvent k Two different types of acid catalysts were tested SA was a solid Silica-Alumina, a Lewis acid-type of catalyst used in petroleum cracking TFA was trifluoroactic acid, a proton acid. 

In some cases a catalyst consists of minute particles of an active material dispersed over a less active substance called a support. The active material is frequently a pure metal or metal alloy. Such catalysts are called supported catalysts, as distinguished from unsupported catalysts, whose active ingredients are major amounts of other substances called promoters, which increase the activity. Examples of supported catalysts are the automobile-muffler catalysts mentioned above, the platinum-on-alumina catalyst used in petroleum reforming, and the vanadium pentoxide on silica used to oxidize sulfur dioxide in manufacturing sulfuric acid. On the other hand, the platinum gauze for ammonia oxidation, the promoted iron for ammonia synthesis, and the silica-alumina dehydrogenation catalyst used in butadiene manufacture typify unsupported catalysts. 

Disulfides and polysulfides are useful for sulfiding hydrotreating catalysts, used in petroleum refining to convert metal oxides to the preferred metal sulfides. Hydrotreating is an essential process in the refining of petroleum. It removes heteroatoms, nitrogen, and sulfur from crude oil and its fractions, formulated into gasoline and diesel (Table 5). 

A catalyst consisting of platinum dispersed on an acidic alumina is a very effective dual function catalyst, used in petroleum reforming of naphtha and also for paraffin isomerization. The conversion of naphtha constituents such as methylcyclopentane, MCP, to benzene, B, is desired in order to increase octane rating. The reaction pathway for conversion of MCP to B is illustrated in Fig. 3 . MCP is first dehydrogenated on a platinum site to the olefin of the same structure. The olefin then transfers to an acidic site where it is isomerized to cyclohexene. This olefin proceeds to a platinum site where it is dehydrogenated to B and H2. In the diagram, vertical movement represents hydrogen subtraction or addition and horizontal movement represents isomerization. 

When minute particles of an active material are dispersed on a less active substance to produce a catalytic effect, such catalysts are called supported catalysts. The active material is usually a pure metal or a metal alloy. Examples of supported catalysts are the platinum on-alumina catalyst used in petroleum reforming and vanadium pentoxide on silica catalyst used in oxidation of sulphur dioxide. 

Some process catalysts used in petroleum and chemical refining may be poisoned when even trace amounts of nitrogenous materials are contained in the feedstocks. This test method can be used to determine bound nitrogen in process feeds and may also be used to control nitrogen... 

The similarity of allophane to the cracking catalysts used in petroleum refining has been recognized by various authors (Fieldes [1962, 1966], Fieldes and Schofield [1960], etc.). This is likely to be another aspect of the same phenonemon organic molecules being adsorbed at reactive sites on allophane surfaces and there undergoing degradation. 

The original performance of the fresh catalyst can be successhiUy restored by proper regeneration to remove this coke. Regeneration allows continued use of the same catalyst for many years. Thus even expensive and sophisticated catalysts can become economical for commercial use in petroleum refining. 

Catalytic Pyrolysis. This should not be confused with fluid catalytic cracking, which is used in petroleum refining (see Catalysts, regeneration). Catalytic pyrolysis is aimed at producing primarily ethylene. There are many patents and research articles covering the last 20 years (84—89). Catalytic research until 1988 has been summarized (86). Almost all catalysts produce higher amounts of CO and CO2 than normally obtained with conventional pyrolysis. This indicates that the water gas reaction is also very active with these catalysts, and usually this leads to some deterioration of the olefin yield. Significant amounts of coke have been found in these catalysts, and thus there is a further reduction in olefin yield with on-stream time. Most of these catalysts are based on low surface area alumina catalysts (86). A notable exception is the catalyst developed in the former USSR (89). This catalyst primarily contains vanadium as the active material on pumice (89), and is claimed to produce low levels of carbon oxides. 

Beginning with the 1975 U.S. automobiles, catalytic converters were added to nearly all models to meet the more restrictive emission standards. Since the lead used in gasoline is a poison to the catalyst used in the converter, a scheduled introduction of unleaded gasoline was also required. The U.S. petroleum industry simultaneously introduced unleaded gasoline into the marketplace. 

The pyrophoricity of nickel-on-sepiolite catalysts after use in petroleum processing operations may be caused by the presence of finely divided nickel and/or carbon. See other pyrophoric catalysts... 

Rhenium is a rare metal with total world production in 2007 estimated at about 50 tonnes. The principal industrial applications of rhenium are in high-temperature alloys used in jet engines and in platinum-rhenium catalysts used in the petroleum industry. In recent years, the demand for rhenium has increased and prices have risen to more than US 10,000 per kg. In late 2008, rhenium was the sixth most expensive traded element (WWW. lipmann.co.u k/fa cts/expe ns i ve. htm I)... 

According to a USEPA survey, many of the more than 150 separate processes used in petroleum refineries generate large quantities of hazardous wastes. Typical wastes generated from refinery processes include bottom sediments and water from crude storage tanks, spent amines, spent acids and caustics, spent clays, spent glycol, catalyst fines, spent Streford solution and sulfur. 

Occurs in nature in abundance the principal forms are bauxites and lat-erites. The mineral corundum is used to produce precious gems, such as ruhy and sapphire. Activated aluminas are used extensively as adsorbents because of their affinity for water and other polar molecules and as catalysts because of their large surface area and appropriate pore sturcture. As adsorbents, they are used for drying gases and liquids and in adsorption chromatography. Catalytic properties may be attributed to the presence of surface active sites (primarily OFT, 02, and AF+ ions). Such catalytic applications include sulfur recovery from H2S (Clauss catalysis) dehydration of alcohols, isomerization of olefins and as a catalyst support in petroleum refining. 

This reaction was first used in petroleum reformation for the synthesis of higher olefins (Shell higher olefin process - SHOP), with nickel catalysts under high pressure and high temperatures. Nowadays, even polyenes with MW > 250,000 are produced industrially in this way. 

The objective of this work was to study the activity of the Monolith catalyst for removing sulfur and nitrogen from a Synthoil process liquid (heavy stock) and Raw Anthracene Oil (light feedstock), and to make a preliminary assessment of the advantages and/or disadvantages of the Monolith catalyst over a commercial catalyst used in the petroleum industry. 

The deactivation of catalysts used in hydrotreating and hydroconversion of heavy petroleum feedstocks is associated with coking and metals deposition. Deactivation by metals has been thoroughly studied [1], but, little is known about deactivation by carbonaceous deposits. The initial decline in activity has often been attributed to this coke formation [2, 3, 4], However, in a recent study [51 it has been shown that coke deactivation can account for more than 50% of the deactivation in resid upgrading. 

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