Patent GB-544642-A (GB)
Title: Catalytic dehydrogenation and aromatization
IPC: C10G59/06
Filed: 1940-09-11
Abstract: 544,642. Catalytic agents and processes. STANDARD OIL CO., and KELLOG CO., M. W. Sept. 11, 1940, No. 14081. Convention date, Sept. 13, 1939. [Class 1 (i)] [Also in Group IV] In the conversion of low knock naphthas into motor fuel of high octane rating by treatment with hydrogen in the presence of non silicous catalysts comprising oxides or sulphides of metals of the VI group under operating conditions within the following specified ranges, viz. temperatures between 860 and 1075‹F., pressure between atmospheric and 450 pounds and space velocities between 0.4 and 10 volumes of liquid naphtha per volume catalyst space per hour, the naphtha is fractionated into a relatively low boiling fraction comprising relatively difficulty, aromatizable compounds and a relatively high boiling fraction which is more easily aromatizable and the low boiling fraction is subjected to severer treatment conditions in the above range while the higher boiling fraction is subjected to milder conditions of re-action within the said range, and the catalyst which is used in a fresh or regenerated condition for conversion of one fraction is also used without regeneration for conversion of the other fraction. The naphtha is preferably fractionated into a fraction containing from 6 to 7 carbon atoms in the molecule and a fraction containing 8-12 carbon atoms in the molecule, fraction containing 4-5 carbon atoms being preferably separated and by-passed round the re-action zones. De-hydrogenation ring closing catalysts specified comprise molybdenum or chromium oxide on alumina with or without oxides of copper, nickel or manganese to facilitate regeneration. Metallates having the Group VI metal in the anion may also be used, e.g. magnesium, aluminium, or zinc chromites or molybdenites; vanadium, cerium, tungsten and uranium oxides &c. are also specified. The catalysts may be employed as fixed beds or as a powder suspensed in the naphtha. The naphtha may he de-hydrogenated prior to fractionation by treatment in presence of de-hydrogenation catalysts at 850-1075‹F. and the hydrogen thus produced, after purification may be used in the subsequent aromatization. Crude naphtha is fractionated in a still 11 into (a) a butane pentane fraction removed overhead through line 12, (b) a hexane-heptane fraction removed through line 13 and an octanenonane-decane fraction removed through line 14. The fraction (b) heated in coil 18 and mixed with hydrogen heated in coil 23 is passed downwardly through reactor 21 to which catalyst is fed through line 25. The aromatized products pass through line 26 to a separator 28 where hydrogen is' separated and re-cycled through line 31 while the liquid product is fed through line 33. The catalyst after being on stream for about 2-20 hours is passed to catalyst chamber 36 where it is used for the conversion of the more easily aromatized fraction which is heated in the coil 39 and injected through line 41 together with hydrogen from line 44. The products from the re-action chambers 21, 36 are condensed and separated from hydrogen in vessel 28, 47 and together with the light fraction from line 12 are blended to give a high octane naphtha in line 34. In the modification shown in Fig. 3 the naphtha is fractionated in tower 11 into separate fractions taken off through lines 13, 14, 14' and these fractions are aromatized by heating them in coils 18, 39, 39<SP>1</SP> and then passing them through re-actors E, F. G, which are super-posed so that the catalyst can be passed in series through the chambers. A further chamber H is provided for regenerating the catalyst. In Fig. 4 the naphtha is de-hydrogenated prior to fractionation by heating it in coil 111 and then passing it into catalytic chamber 114. the products being separated from hydrogen in chamber 119 and then fractionated in tower 128. Separate fractions are withdrawn through lines 130, 131 heated in coils 147, 135 and subjected to different aromatizing conditions in re-actors 138 and 150. The products are finally fractionated in tower 134 from which an anti-knock gasoline is withdrawn through line 161 and is blended with the fraction taken overhead from tower 128 through line 129. Re-cycle lines 145, 146, 163 are provided for recycling fractions from the tower 128, 134 and the re-actors 138 and 150 to the de-hydrogenation stage or to any subsequent stage of the process.