GB530250A - Improvements in or relating to the manufacture of motor fuels - Google Patents

Abstract

530,250. Alkylation of isoparaffins. TEXACO DEVELOPMENT CORPORATION. May 31, 1939, No. 16033. Convention date, June 25, 1938. [Class 2 (iii)] Isoparaffins are alkylated with olefins by a process which comprises subjecting a normally gaseous hydrocarbon mixture of olefins and normal paraffins to contact with sulphuric acid under non-alkylating conditions to absorb the olefins, removing the unreacted normal paraffins, passing to an alkylation zone and reacting the olefine in the presence of concentrated sulphuric acid with an isoparaffin under alkylating conditions. In the preferred form of the invention the olefine is separated into fractions containing the same number of carbon atoms by selectively absorbing the olefins in sulphuric acid and then alkylating isoparaffins of boiling points approximating to that of gasolin in the presence of sulphuric acid as alkylation catalyst. The olefins which are used in the present invention are preferably obtained from the cracking of hydrocarbon oils and gasses, the dehydrogenation of normally liquid or normally gaseous hydrocarbons or hydrocarbons which are normally gaseous and are obtained from operations such as the synthesis of hydrocarbon oils from water gas. The apparatus used for the separation of the fractions of the olefins is shown in the drawing. The hydrocarbon mixture is charged through line 114 and may consist of a mixture of olefins together with in some cases some paraffins of the same molecular weight. The hydrocarbon mixture is passed through a series of absorption vessels 110, 111, and 112, charged with sulphuric acid of appropriate strength to absorb one of the fractions of olefins present in the initial hydrocarbon mixture. The unabsorbed olefins pass through line 124 to a second series of absorption vessels where it is contacted with sulphuric acid of somewhat greater concentration such that a second and higher fraction of olefins are absorbed. The absorbed olefins are passed through line 125 to an alkylation apparatus in which the alkyl sulphuric acid solution is contacted with more concentrated sulphuric acid which acts as an alkylation catalyst and also with an appropriate isoparaffin. The alkylation is conducted in vessels 130 and 138. After alkylation the products are neutralized and washed in vessels 153 and 158 and fractionated in vessel 164. Arrangements are present whereby a portion of the charge from the absorption vessels may be recycled. In a modification the alkyl sulphuric acid solution may be passed through line 174 to polymerization vessel 175 and thence to a fractionator 178 and condenser 182. The condensed product which may consist of a dimer of the original olifinic fraction is passed through line 184 to join the higher fractions of olefins passed on from the absorption towers. The materials so passed on whether they are higher olefine fractions or polymerization products are treated. in the same manner as described above and yet higher fractions similarly passed on through line 251 to be similarly treated. Specification 515,367 is referred to. The Specification as open to inspection under Sect. 91 includes also the separation of the olefins by the use of a selective polymerizing agent particularly by selective polymerization with a solid phosphoric acid catalyst. The apparatus used when the separation of the olefins is effected by selective polymerization is shown in Fig. 1 (Cancelled). Olefins are introduced through the line 5 to a coil 9 in a heater 10 and thence to a polymerizer 13 containing a calcined mixture of pyro-phosphoric acid and kieselguhr. The reaction products are passed to a fractionator 15, from which the liquid products are separated by line 20 to an alkylation operation. The gaseous olefins after separation of the polymers are withdrawn from the polymerizer 15 through the line 22 and then passed to further and more drastic polymerization process. This is followed in turn by a fractionator operation and in this way there may be withdrawn through the lines 17, 33, and 47 a series of fractions of polymerized olefins, each fraction comprising olefins of approximately the same number of carbon atoms. These fractions are charged into tanks 54,55 and 56 from which they may be drawn off and passed by line 61 to the alkylation vessels 70 and 74. Here they are contacted with an appropriate isoparaffin and with a sulphuric acid catalyst introduced through passages 65 and 67 respectively. The products are passed to a separator 78 from which arrangements are present whereby part of the charge may be recycled, and ports neutralized and washed. This subject-matter does not appear in the Specification as accepted.