Are there any antacids or acid/base reactions that do not give off CO2, but rather some other harmless gas?

Question

For example, Neutralization reactions like these below (but that DO NOT have CO2 as an end product, but rather some other harmless gas):

HC2H3O2 + NaHCO3 ===> NaC2H3O2 + H2CO3 H2CO3 ===> H2O + CO2

MgCO3(s) + 2 HCl(aq) -----> MgCl2(aq) + H2O(l) + CO2(g)

Answer 1

Examples of antacids (brand names may vary in different countries).
Aluminum hydroxide (Amphojel®, AlternaGEL®)
Magnesium hydroxide (Phillips’® Milk of Magnesia)
Aluminum hydroxide and magnesium hydroxide (Maalox®, Mylanta®)
http://en.wikipedia.org/wiki/Antacid

Answer 2

There aren't too many other acids and bases that give off harmless gases. About the only one I know are with acetate salts; the acetate ion hydrolyzes to acetic acid in highly acid solutions.