Aromatic hydrocarbon cracking

The solubility parameter is in the range 18.4-19 MPa and the polymer is predictably dissolved by halogenated and aromatic hydrocarbons of similar solubility parameter. Stress cracking can occur with some liquids. 

Natural gas and crude oils are the main sources for hydrocarbon intermediates or secondary raw materials for the production of petrochemicals. From natural gas, ethane and LPG are recovered for use as intermediates in the production of olefins and diolefms. Important chemicals such as methanol and ammonia are also based on methane via synthesis gas. On the other hand, refinery gases from different crude oil processing schemes are important sources for olefins and LPG. Crude oil distillates and residues are precursors for olefins and aromatics via cracking and reforming processes. This chapter reviews the properties of the different hydrocarbon intermediates—paraffins, olefins, diolefms, and aromatics. Petroleum fractions and residues as mixtures of different hydrocarbon classes and hydrocarbon derivatives are discussed separately at the end of the chapter. 

Propane cracking is similar to ethane except for the furnace temperature, which is relatively lower (longer chain hydrocarbons crack easier). However, more by-products are formed than with ethane, and the separation section is more complex. Propane gives lower ethylene yield, higher propylene and butadiene yields, and significantly more aromatic pyrolysis gasoline. Residual gas (mainly H2 and methane) is about two and half times that produced when ethane is used. Increasing the severity... 

In Europe naphtha is the preferred feedstock for the production of synthesis gas, which is used to synthesize methanol and ammonia (Chapter 4). Another important role for naphtha is its use as a feedstock for steam cracking units for light olefins production (Chapter 3). Heavy naphtha, on the other hand, is a major feedstock for catalytic reforming. The product reformate containing a high percentage of Ce-Cg aromatic hydrocarbons is used to make gasoline. Reformates are also extracted to separate the aromatics as intermediates for petrochemicals. 

The Ce-Cg aromatic hydrocarbons—though present in crude oil—are generally so low in concentration that it is not technically or economically feasible to separate them. However, an aromatic-rich mixture can be obtained from catalytic reforming and cracking processes, which can be further extracted to obtain the required aromatics for petrochemical use. Liquefied petroleum gases (C3-C4) from natural gas and refinery gas streams can also be catalytically converted into a liquid hydrocarbon mixture rich in C6-C8 aromatics. 

Catarole Also spelled Catarol. A process for making aromatic hydrocarbons and olefins by cracking petroleum fractions over copper turnings. Invented by C. Weizmann in England in... 

Hall (3) An early process for making aromatic hydrocarbons by thermally cracking petroleum naphtha. See also Rittman. 

Kureha/Union Carbide A process for cracking crude oil to olefins and aromatic hydrocarbons, using steam superheated to 2,000°C. Reaction time is only 15 to 20 milliseconds. 

MHC [Mitsubishi hydrocracking] A process for making benzene and other aromatic hydrocarbons by hydrogenating cracked petroleum fractions. 

PCC [Partial combustion cracking] Not to be confused with precipitated calcium carbonate. A process for cracking crude petroleum or heavy oil to a mixture of olefins and aromatic hydrocarbons. The heat carrier is steam, produced by the partial combustion of the feed. Developed by Dow Chemical Company. It was piloted in 1979 and a larger plant was built in Freeport, TX, in 1984. 

Diluents, mainly volatile aliphatic or aromatic hydrocarbons such as petroleum ether, dodecylbenzene or glycols, are often added to PVC pastes to lower the viscosity. These do not have a gelling effect and are evaporated off before gelation is commenced to prevent fine cracks or bubbles in the coating. Pigments for this application are required to have adequate resistance to the solvents used at the processing temperatures. 

Most lignin is now burnt for heat and power, but process options are available to depolymerize the phenolic material by thermal cracking or using base treatments [7]. In consecutive steps the products can be converted into aromatic hydrocarbon feeds. 

Polysulfones are handicapped by light and UV sensitivity requiring an efficient protection for outdoor exposure sensitivity to environmental stress cracking and attacks by chemicals such as aromatic hydrocarbons, chlorinated solvents and ketones the cost (justified by the performances) sometimes an insufficient fire resistance, but special grades are marketed. 

PPSU alloys have the best hydrolytic stability, thermal stability and oxidation resistance. This resin is resistant to mineral acids and alkalis, while ketones, chlorinated hydrocarbons and aromatic hydrocarbons may cause stress cracking. 

Peter Hervey Given was bom in 1918. He was educated at Oxford University, receiving a B.A. in Chemistry in St. Peter s Hall, Oxford, and the M.A. and D.Phil. in the Dyson Perris Laboratory under the direction of Professors D. LI. Hammick and Sir Robert Robinson (who was the Nobel laureate in chemistry for 1947). Given s thesis research dealt with carbonium ion reactions of aromatic hydrocarbons on cracking catalysts (1-. ... 

VGO contains more satnrate and less aromatic hydrocarbons than resid. VGO also has a lower boiling point range. As a result, VGO is easier to crack and generates less bottoms oil. In this section, the yield structure of VGO will be compared to that of resid, and the differences are discnssed. 

At higher temperatures, C—H and C—C bonds may be similarly broken. Thus, zeolite catalysts may be used for (i) alkylation of aromatic hydrocarbons (cf. the Friedel-Crafts reactions with AICI3 as the Lewis acid catalyst), (ii) cracking of hydrocarbons (i.e., loss of H2), and (Hi) isomerization of alkenes, alkanes, and alkyl aromatics. 

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