| 摘要 |
In the regeneration of zeolitic molecular sieves which have been used to separate vapour mixtures of normally liquid adsorbable hydrocarbons with non-adsorbable hydrocarbons, non-adsorbed and surface adsorbed hydrocarbons are purged from the zeolite bed with a purge gas, before desorption to recover the adsorbed fraction is effected. Purging is effected, preferably at a temperature equal or less than and not longer than for the first stage, with a normally gaseous medium such as isobutane or nitrogen, or by vacuum purging at 0 to 100 mm. Hg, and desorption is effected with for example n-butane or hydrogen. Adsorption is generally effected at 0 DEG to 600 DEG C., and is preferably discontinued before breakthrough. The effluents from the purging and adsorption stages are combined. In Example 1 a 25%/75% weight mixture of heptane and iso-octane is contacted with a 5 molecular sieve at 200 DEG C. purging is effected at 10 to 20 mm. Hg at 200 DEG to 230 DEG C., and desorption is effected at 300 DEG to 330 DEG C. with hydrogen. In Example 2 a desulphurized light naphtha comprising C6-C9 hydrocarbons is contacted with a 5 molecular sieve at 250 DEG C., purging is effected at 250 DEG C. with nitrogen, and desorption is effected at 250 DEG C. with hydrogen.ALSO:The separation of mixtures of normally liquid adsorbable hydrocarbons with non-adsorbable hydrocarbons is effected by means of a zeolitic molecular sieve. Non-adsorbed and surface adsorbed hydrocarbons are purged from the zeolite bed with a purge gas, before desorption to recover the adsorbed fraction is effected. Purging is effected, preferably at a temperature equal to or less than and for not longer than, the adsorption, with a normally gaseous medium such as isobutane or nitrogen, or by vacuum purging at 0 to 100 mm Hg. and desorption is effected with, for example, n-butane or hydrogen. Adsorption is generally effected at 0 DEG C. to 600 DEG C. and is preferably discontinued before break-through. The effluents from the purging and adsorption steps are combined. In Example 1 a 25%/75% weight mixture of heptane and isooctane is contacted with a 5 molecular sieve at 200 DEG C.; purging is effected at 10 to 20 mm Hg at 200 DEG C. to 230 DEG C., and adsorption is effected at 300 DEG C. to 330 DEG C. with hydrogen. In Example 2 a desulphurised light naphtha comprising C6-C9 hydrocarbons is contacted with a 5 molecular sieve at 250 DEG C.; purging is effected at 250 DEG C. with nitrogen, and desorption is effected at 250 DEG C. with hydrogen. |
