Phosphorus-Containing Mesoporous Carbon Acid Catalyst for Methanol Dehydration to Dimethyl Ether

Catalytic dehydration of methanol on an acid carbon catalyst prepared by chemical activation of olive stone with H 3 PO 4 is reported. This preparation methodology produces carbons with a well-developed porous texture and highly thermally stable phosphorus surface complexes in the forms of C–O–PO 3 and C–PO 3 . These P groups confer the carbon with a high oxidation resistance, surface acid, and redox sites. In the absence of oxygen, the catalyst experiment demonstrated a gradual deactivation due to coke deposition on the strong acid sites (P–OH) and reduction of the moderate-strength acid P-surface groups (from C–O–P to C–P type ones). The novelty of this research concerns the high catalytic stability in air atmosphere of this type of carbon with a steady-state methanol conversion of 20% at 300 °C and selectivity towards dimethyl ether of 95%. The presence of oxygen in the reaction gas avoids coke deposition by continuous (re)oxidation of reduced P-surface groups, without gasification of the carbon catalyst.