关键词: 甲醇水蒸气重整, 两段重整工艺, 甲醇液相空速, 反应器, 固定床, 燃料电池

Abstract:

Methanol is an ideal hydrogen carrier because it keeps liquid state at normal temperature and pressure and has a very high hydrogen-carrying density. The design of methanol reforming reactors is important for the methanol online reforming system. For methanol reforming reactors, the CO concentration in reformate is high at high reaction temperatures that is not conducive to subsequent deep CO removal. But at low temperature, the low methanol conversion and liquid hourly space velocity (LHSV) s results in low catalyst utilization and large reactor volumes. Hence, a two-stage reforming process with the first isothermal section operating at 300℃ and the adiabatic second section working from 300℃ to 220℃, was proposed. A simulation study on Aspen Plus proved that the reactor was theoretically feasible. The experimental study was then carried out in a fixed bed reactor and the results showed that under conditions of complete methanol conversion, the methanol LHSV for this two-stage process was 4.08h^-1, the CO concentration in reformate was 0.56% and the reforming hydrogen production efficiency was 108.98mL/(min·mL catalyst). The isothermal reforming process at 220℃ had a methanol LHSV of 1.5h^-1, a CO concentration of 0.40% in reformate and a reforming hydrogen production efficiency of 44.89 mL/(min·mL catalyst). The two-stage process achieved higher reforming hydrogen production efficiency at higher LHSV, lower catalyst usage and a more compact reformer structure. At the same time, the CO concentration of this two-stage process was much lower than that of the isothermal reforming process at 300℃ (1.77% at 300℃) at the same LHSV. Therefore, the two-stage process proposed in this paper was of great importance to obtain high hydrogen production efficiency and low CO concentration.

Key words: methanol steam reforming, methanol liquid hourly space velocity, a two-stage reforming process, reactors, fixed-bed, fuel cells