Tripotassium phosphate process

The use of a tripotassium phosphate solution for H2S removal was introduced by the Shell Envelopment Company (Rosenstein and Kramer, 1934). The process has been displaced by alkanolamine and other processes for refinery and natural-gas purification and is no longer offered or supported by Shell (Shell Development Co., 1992). 

The U.S. Bureau of Mines studied the process to evaluate the Alkacid dik solution as a selective absorbent for hydrogen sulfide in the presence of carbon dioxide, and the results were compared with those of other absorbents tested in the same apparatus. The solution capacity of the AUcacid solution tested has been compared with that of the 35% tripotassium phosphate solution in Figure 5-44, which demonstrates the effect of the CO2/H2S ratio on the absorptive capacity of both solutions. It will be noted that the Alkacid solution takes up appreciably more H2S particularly at low CO2/H2S ratios. Although its capacity is higher, the Alkacid solution was found to be somewhat less selective than tripotassium phosphate. 

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