| 摘要 |
The steam and hydrocarbon feed to be reacted over an active nickel catalyst at 550 DEG to 850 DEG F. (288 DEG to 454 DEG C.) to produce a hydrogenrich gas are first passed over a spent nickel catalyst which has been spent in the main reaction but retains residual activity, e.g. it may retain 20 to 50% of the original active nickel surface area. The spent catalyst acts to remove sulphur and coke-forming materials and produces some hydrogen for mixing with the unreacted steam and feed. The reaction over the spent catalyst is carried out at lower temperatures, e.g. 400 DEG to 700 DEG F. (204 DEG to 371 DEG C.) than the main reaction. The active catalyst is preferably of the co-precipitated type and comprises 40 to 60% by weight nickel with the rest alumina or silica, a promoter metal being added. The feed may be liquid, e.g. C5 to C8 paraffins, or gaseous (e.g. natural gas) or a mixture thereof. Two apparatus are described in which the spent and active catalyst are in the same vessel (see Figs. 1 and 2, not shown), and a flow diagram is provided which illustrates the use of separate vessels, each vessel acting in turn as the main and the initial catalyst vessel (see Fig. 3, not shown). Oxidation of the spent catalyst may be avoided by gas blanketing, e.g. with N2, N2 and CO2, H2, or inert hydrocarbon. Two specific examples are described in which H2-rich gases are produced at low conversions (i.e. up to 40% conversion of hydrocarbon) and CH4-rich gases at higher conversions, the degree of conversion depending on the space velocity, which may be controlled. |
