Patent GB-745520-A (GB)
Title: Improved hydroforming process
IPC: C10G59/02
Filed: 1952-08-07
Abstract: Hydrocarbons boiling in the motor fuel range are hydroformed by contacting them in a first zone with a hydroforming catalyst comprising platinum or palladium deposited on a halogen-free support of low hydrocracking activity in the presence of hydrogen at a temperature from 800 DEG  F. to 900 DEG  F. and a pressure from 500 to 750 p.s.i.g., and transferring at least a portion of the product and hydrogen from the first zone to a second zone wherein they are contacted under more severe conditions with a hydroforming catalyst comprising platinum or palladium deposited on a support of low hydrocracking activity at a temperature from 880 DEG  F. to 930 DEG F. and a pressure from 20 to 400 p.s.i.g.  The catalyst support in the first stage may contain up to 6 per cent of silica but the addition of hydrogen fluoride or other hydrogen halide to the catalyst support must be avoided.  Specified catalysts for the first stage are platinum or palladium upon activated alumina or upon alumina gel. The platinum or palladium may be deposited on the support by impregnating the latter with a solution of a soluble compound of the catalytic metal and treating with a precipitant, heating to decompose the catalytic metal sulphide, or reducing the precipitated sulphide with hydrogen or other reducing agent. Before placing the catalyst on stream it is advisable to further reduce it by treating with hydrogen or hydrogen-rich gas at elevated temperature.  Specified catalysts for the second stage are platinum or palladium on alumina gel, on activated alumina containing up to 6 per cent silica, or on zinc aluminate spinel. The catalyst in each stage preferably contains from 0.25 to 1.0 per cent of platinum or from 0.5 to 2 per cent palladium. Hydrogen is provided in the reaction either by supplying fresh hydrogen directly or preferably by recycling the process gases. Contact of the hydrocarbon feed stock with the catalyst may be effected in either a fixed or in a moving or fluidized bed and contact in the two stages may be the same or different, e.g. fixed bed in the first stage and moving or fluidized bed in the second. The liquid space velocity in the first stage is preferably from 2-5 volumes and in the second stage is preferably from 0.75-2.0 volumes feed per volume of catalyst per hour whilst the hydrogen dilution in the first stage is preferably from 4-6 mols. and in the second stage is preferably from 5-9 mols. hydrogen per mol. of hydrocarbon feed.  Two types of procedures in which light or heavy naphtha feeds may be treated are described and illustrated. In the first type the total product from the first stage is conducted through a pressure reducer and furnace into the second stage to form a high octane number hydroformate.  In the second type the total product from the first stage is passed through a cooler and separator to separate C5 and lower boiling products from the C6 + hydrocarbons and the former products are then passed to a further cooler and separator to separate C4 and C6 products, which are conducted to gasoline blending or storage, from the C1-C3 products and hydrogen. The C5 + hydrocarbons from the first separator are then admitted along with hydrogen and the C1-C3 fractions (a part of which may be recycled to the first stage) to the second reaction zone to yield the liquid hydroformate product. An example is given for the treatment of a heavy virgin naphtha from mixed crudes, the catalyst in the stage being obtained by impregnating alumina with an aqueous solution of chloroplatinic acid, followed by treatment with hydrogen sulphide, pilling, calcining at 950 DEG  F. and then reducing with hydrogen while raising the temperature to that desired in the first reaction stage.  The temperature in the first and second stage is 900 DEG  F. while the pressures are 700 and 200 p.s.i.g. respectively. Specification 662,002 is referred to.