Characterization of acid-base centers and catalytic dehydration of 2,3-butanediol (BOO) was performed over a wide range of silica-supported alkali phosphates (M_P/SiO2; M = Na, K, Cs; M:P = 0.5-3 mol:mol). Selectivity to 1,3-butadiene (BD) and 3-butene-2-ol (3B2OL) formed by elimination correlates with the densities of conjugated acid-base pairs and increases in the order Na < K approximate to Cs. Selectivity to 2,3-epoxybutane (BTO) formed by de-hydrative epoxidation increases with the M/P ratio in the order Na < K approximate to Cs. Methyl ethyl ketone (MEK) and isobutyraldyde (IBA) formed by the rearrangement are produced by isolated Bronsted acid centers. Conjugated acid-base pairs are probably composed of the end groups of polyphosphates having both acid P-OH and base P-O-center dot center dot center dot M+ moieties. Isolated Bronsted acid centers are probably silica grafted phosphoric acid molecules at low M/P and -PO(OH)(2) end groups of oligophosphates at M/P > 1.5. Deactivation rate increases with the increase of M/P ratio in order Na < K < Cs. Deactivation patterns imply that sites responsible for elimination are active in dehydrative epoxidation. Dehydration of 3B2OL smoothly proceeds to BD, but the catalysts deactivate faster compared to BDO dehydration.