GB857587A - Method of making hydrogen and uses thereof - Google Patents

Abstract

Hydrogen is produced by decomposing a hydrocarbon or interacting carbon and steam at a temperature of 850-1600 DEG F., preferably 1300 DEG F., in the presence of cobalt molybdate, or a mixture of cobaltous oxide and molybdic trioxide, as catalyst. The mol ratio of cobaltous oxide to molybdic trioxide is 0.1:1 to 1:0.1. The pressure is 0-1000 p.s.i.g., preferably atmospheric-200 p.s.i.g. The reactant flow rate is 1-500 v./v./hr., preferably 50-100 v./v./hr. The catalyst may be supported on alumina, zirconia, magnesia, silica, silica-alumina, or kieselguhr, e.g. in an amount of 1.0-25%, preferably in an amount of 15%. The catalyst may be in a fixed bed. Alternatively it may be fluidised in a vaporous or gaseous hydrocarbon or steam, or suspended in a liquid hydrocarbon. 0.25-1 mol of steam per atom of carbon in the hydrocarbon may be present. The hydrocarbon may be methane, ethane, propane, a C4-C6 hydrocarbon, a mono- or diolefin, natural gas, gasoline, kerosene, gas oil, a naphthene, crude petroleum, a crude petroleum residue, tar or asphalt. 1-50% of free carbon based on the catalyst, and 1 mol of steam per atom of carbon, may be employed. The carbon may be in the form of coal or coke. According to Fig. 1 (not shown), methane, or natural gas, optionally together with steam, is preheated and then passed through one or both of two reactors containing cobalt molybdate or alumina and arranged in parallel. One reactor may be on stream while the other is being regenerated by the passage of steam therethrough. The product or unreacted methane separated therefrom may be recycled. Methane may be separated by selective adsorption and/or fractional distillation. Methane may be selectively adsorbed on a solid adsorbent at a temperature of -150-600 DEG F. and a pressure of 15-500 p.s.i.g. in a separation zone and stripped therefrom in a separate stripping zone by means of a steam heating coil. According to Fig. 2 (not shown), natural gas is preheated by indirect heat exchange with product hydrogen, is contacted with a fluidised bed of cobalt molybdate catalyst at a temperature of 1300 DEG F. &c. and a pressure of 25 p.s.i.g. and the product is separated from entrained catalyst in one or more cyclones. The catalyst is passed from the reaction zone to a stripping zone wherein it is stripped with steam, then to a regeneration zone together with the stripped gas wherein combustion is effected with added oxygen, e.g. at a temperature of 1100-1800 DEG F. and a pressure of 0-750 p.s.i.g., and then recycled to the reaction zone. Tables are given specifying various temperatures, pressures, flow rates, reaction times, steam concentrations and product analyses. The hydrogen-producing process may form part of a cyclic process for the production of hydrocarbons having a comparatively high hydrogen to carbon ratio, e.g. gasoline, and heating and lubricating oil, from hydrocarbons having a comparatively low hydrogen to carbon ratio. In this cyclic process gaseous hydrocarbon is converted according to the invention into hydrogen, this hydrogen is admixed with vaporized liquid feed hydrocarbon, and the mixture is passed over a liquid hydrocarbon conversion catalyst to produce the liquid hydrocarbon product together with gaseous hydrocarbon which is separated and recycled. The latter conversion may be a hydrofining, hydrocracking, hydroforming or hydrogenation operation. A gaseous hydrocarbon, e.g. methane, ethane or propane, may be introduced into the cycle either with the feed hydrocarbon or to the gaseous product after the liquid hydrocarbon conversion step. The temperature during conversion may be 500-1000 DEG F. and is preferably 600-900 DEG F. The pressure may be 15-900 p.s.i.g., and is preferably 15-600 p.s.i.g. The space velocity may be 0.5-15 v./v./ hr. The catalyst may be chromium, nickel, molybdenum, cobalt, platinum, palladium, tungsten, or titanium, or an oxide or sulphide thereof, or cobalt molybdate, or a mixture of two or more thereof, and may be supported. The catalyst may comprise 1-50% and is preferably 15% of the weight of catalyst and support. The catalyst may be in a fixed or fluidised bed. According to Fig. 5 (not shown), a crude residue containing asphaltic components, optionally together with natural gas, is preheated, admixed with recycled product hydrogen, and passed through a fixed bed conversion catalyst of cobalt molybdate or platinum. The converted hydrocarbon is separated into liquid hydrocarbon product, which is subjected to fractional distillation, and gaseous hydrocarbon, which is passed, optionally together with natural gas, through a fixed bed of cobalt molybdate catalyst to produce hydrogen, which is recycled. All or a portion of the separated gaseous hydrocarbon may be scrubbed before passing to the hydrogen-producing step. According to Fig. 3 (not shown), heavy hydrocarbons are passed through a static bed so as to deposit carbon, whereafter steam is passed through so as to remove the carbon. According to Fig. 4 (not shown) coal is reacted with steam in a fluidised bed, the catalyst being recycled to the bed after separation of ash in a separate fluidised bed.