Catalysts regeneration after sulfur poisoning

Figure 13.10 DTA-GC curves of Ni-LajOj-Pd/AljOj catalyst after regeneration following sulfur poisoning (10)...

Some other results of other TPH experiments can be seen in Table 1. In atmospheric-pressure tests at 900°C with 500 ppm HjS in the gas phase, sulfur was not desorbed from Catalyst Al. The same phenomenon was noticed in the tests performed at 900°C under 5 bar pressure with Catalysts A2 and C. In addition, when the sulfur content of the catalyst beds was analyzed after TPH experiments, it was observed that only a small amount of sulfur was present on the catalyst. This observation indicates that sulfur adsorption is not completely reversible, but that part of the adsorbed sulfur remains on the catalyst. The effect of this phenomenon was also observed when a catalyst was regenerated by removal of HjS to the gas mixture in fixed-bed poisoning tests. The catalyst activity did not reach the original level (with no HjS in the gas) especially in ammonia decomposition. The analysis of the sulfur content of the bed showed that a small amount of sulfur was still present on the catalyst. 

Purification of synthesis gas. The sulfur- and carbon-containing compounds in synthesis gas must be removed in order to avoid the poisoning of catalysts in the following processes. Sulfur and carbon containing compounds are absorbed by different solvents. The used solvents are regenerated by desorption and H2S (or element S) and carbon dioxide are recovered. The trace amounts of carbon monoxide and carbon dioxide which remained in synthesis gas is removed via the reaction of methanation or other methods. After a series of purifications, the content of carbon monoxide and carbon dioxide in the synthesis gas are on the levels of ppm (1 ppm = 1 ml m ). 

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