Gasoline Hydrodealkylation

ABB Lummus Global Benzene Toluene rich stream/pyrolysis gasoline Hydrodealkylation produces high-purity product, single-step process, no hydrotreating 29 1998... 

Properties. Table 4 contains typical gasoline quaUty data from the New Zealand plant (67). MTG gasoline typically contains 60 vol % saturates, ie, paraffins and naphthenes 10 vol % olefins and 30 vol % aromatics. Sulfur and nitrogen levels in the gasoline are virtually lul. The MTG process produces ca 3—7 wt % durene [95-93-2] (1,2,4,5-tetra-methylbenzene) but the level is reduced to ca 2 wt % in the finished gasoline product by hydrodealkylation of the durene in a separate catalytic reactor. 

The main producers of benzene in Canada are the Nova Corp. of Alberta, Petro-Canada, Inc., and Shell Canada Ltd. These three companies have an armual capacity of 567,000 t. Most Canadian benzene is obtained from catalytic reformate, pyrolysis gasoline, and hydrodealkylation. Coal is not an important source of benzene in Canada. 

Some of the principal Japanese producers of benzene are Mitsubishi Petrochemical Co., Ltd., Nippon Steel Chemical Co., Ltd., Sanyo Petrochemical Ltd., and Idemitsu Kosan Ltd. Until 1967, the main source of Japanese benzene was coal-based. Today, approximately 40—45% of benzene production in Japan is based on pyrolysis gasoline (74), about 40% catalytic reformate, and the remainder coke oven light oil and thermal hydrodealkylation. 

Raw materials for obtaining benzene, which is needed for the production of alkylbenzenes, are pyrolysis gasoline, a byproduct of the ethylene production in the steam cracking process, and coke oven gas. Reforming gasoline contains only small amounts of benzene. Large amounts of benzene are further produced by hydrodealkylation of toluene, a surplus product in industry. 

Pyrolysis gasoline gasoline produced by thermal cracking as a byproduct of ethylene manufacture. It is used as a source of benzene by the hydrodealkylation process. 

Table 8.9 shows the non-fuel uses of toluene. Some of the toluene goes into gasoline depending on its supply and price compared to other octane enhancers. Of the other uses of toluene about half is converted into benzene by hydrodealkylation, though this amount varies with the price difference between benzene and toluene. 2,4-Toluene diisocyanate (TDI) is a monomer for polyurethanes. Included in miscellaneous uses is 2,4,6-trinitrotoluene (TNT) as an explosive. 

EB-poor C8 aromatics cuts are produced which favors further pX separation Low-value toluene and C9+ aromatics (that are generally sent to the gasoline pool because of their high octane number) are transformed into high value pX Toluene hydrodealkylation units can be easily revamped into TDP or transalkylation units... 

Chronologically, the effon was im tially dirreted towards a better petrochemical upgrading of toluene and m-xylene, which continue to be used as solvents and in the gasoline pool. Toluene is thus converted to benzene by hydrodealkylation. Through i omerizatioo,. m-.xyiene yields the onho and para isomers in proportions corresponding to thermodynamic equilibrium in the reaction conditions, namely a mixture of Cg from which the... 

Derivation (1) Hydrodealkylation of toluene or pyrolysis of gasoline (2) transalkylation of toluene by disproportionation reaction (3) catalytic reforming of petroleum (4) fractional distillation of coal tar. 

Benzene. Benzene is derived from several sources. A small amount is still recovered from coke oven by-product streams. However, the primary sources are from the catalytic refonning of petroleum fractions rich in naphthenes (see Section 6.2.1.7, above), recovery from aromatic concentrate (pyrolysis gasoline) produced as a by-product of ethylene manufacture, hydrodealkylation of... 

A new generation of so-called regenerative processes emerged with the development of multimetallic catalyst systems. They operate by continuous withdrawal and regeneration of the catalyst, which is then recycled to the reactors. This technology applies to the manufacture of gasoline and specifically to that of aromatics. This is because it can withstand more severe treatment conditions, which allow intensive cyclization of the paraffins, the removal of those that subsist by hydrocracking, and the hydrodealkylation of the heavier compounds,... 

Hydrodealkylation of a pyrolysis gasoline. Economic data (France conditions, mid-1986)... 

The requirement for benzene is over 6Mt per annum in the U.S.A., somewhat lower in western Europe. Coal-tar operations make only modest contributions. In western Europe the main source is pyrolysis gasoline, whereas catalytic reforming (section 12.2.2.3) is the main source in the U.S.A., where the catalytic (clay) or thermal hydrodealkylation of toluene is also more important. 

---