Hydrogen production characteristics of methanol partial oxidation under sprays with ultra-low Pt and Pd contents in catalysts

Abstract

The hydrogen production performances of the partial oxidation of methanol (POM) under sprays are investigated. Three different catalysts of Pt/Al2O3, h-BN-Pt/Al2O3, and h-BN-Pd/Al2O3 with ultra-low Pt and Pd contents (0.2 wt%) are utilized, and the influence of the O2-to-methanol molar (O2/C) ratio on POM is examined. It is found that POM can be triggered in cold start using the Pt/Al2O3 and h-BN-Pt/Al2O3, whereas the h-BN-Pd/Al2O3 needs to be preheated to drive POM. Increasing the O2/C ratio raises the reaction temperature. The maximum H2 yield is always located at O2/C = 0.6, which stands for the transition point of the chemical reaction dominated by partial oxidation to combustion. Once the O2/C ratio is 0.7, almost all methanol is consumed in three catalysts. Overall, the H2 production under the aids of the catalysts is characterized by h-BN-Pt/Al2O3 > Pt/Al2O3 > h-BN-Pd/Al2O3, revealing the better performance of Pt than Pd. The thermodynamic analysis indicates that the theoretical H2 yield declines with rising the O2/C ratio, whereas the measurements suggest that the H2 production increases. For the h-BN-Pt/Al2O3 catalyst, its maximum performance, namely, the ratio of the experimental H2 yield to the theoretical one, develops at O2/C = 0.8 where the value is beyond 99%. However, the maximum H2 yield of 1.66 mol (mol methanol)−1, corresponding to the performance of 91.3%, is located at O2/C = 0.6 which is recommended for operation. The obtained results and findings can provide useful insights into the application of POM for hydrogen production in industry.