Alkali‐alumina sorbents for high‐temperature removal of SO₂

Abstract

The high-temperature removal of SO, by sorbents consisting of sodium and lithium salts supported on a-Al,O, has been investigated with emphasis on the chemistry of regeneration. The sulfated sorbents were regenerated by reduction with CO at 700-800°C in a thermogravimetric analyzer and a packed-bed microreactor. Sulfur removal from the sorbent and distribution of gaseous products were measured at different alkali loadings, temperatures, and CO concentrations. The results are interpreted in terms of a network of reactions wherein alumina is important as a catalyst and as a reactant. During regeneration sulfate is converted to aluminate and sulfide, the fraction of aluminate defining the extent of regeneration. The rate and extent of sulfur removal increase with the ratio of alumina to alkali and are higher in the presence of lithium. The product gas consists of SO,, COS, and elemental sulfur, the latter compound constituting up to 35% of the sulfur removed.

Consequences of Combinatorial Studies of Positive Electrodes for Li-ion Batteries

“…The main concern with respect to alumina is that it reacts with lithium carbonate to form LiAlO 2 , a process which has been observed to go to completion at 700 • C [67]. Magnesia shows no such reaction, but it is hygroscopic and porous, thereby requiring large quantities of stearic acid to prevent the water in the solutions from entering the substrate before the co-precipitation reaction takes place.…”

Alternative formulations of regenerable flue gas cleanup catalysts

“…Barealuminawill absorb SO 2 butithasbeen shown that thecapacity isincreased withtheaddition ofalkali. [8][9][10][11]13 Thesesorbents will also scrubNO x fromtheflue gasasweil, makingthemveryattractive flue gascleanup catalysts. with a higher concentration of basic sites than does doping with Na+.…”

Enhancement of SO2 sorption on lime by structure modifiers

“…Two types of sorbents have been considered: nonregenerable (throwaway) and regenerable. Although there has been some research on regenerable sorbents (Gavalas et al, 1987;Cho and Lee, 1983;Groenendaal et al, 1976;Town et al, 1970;Yang and Shen, 1979), the bulk of the study has been on the use of limestone and dolomite as inexpensive throwaway sorbents.…”