Fuel, Vol.222, 599-609, 2018
Hydrogen production characteristics of methanol partial oxidation under sprays with ultra-low Pt and Pd contents in catalysts
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 O-2-to-methanol molar (O-2/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 O-2/C ratio raises the reaction temperature. The maximum H-2 yield is always located at O-2/C = 0.6, which stands for the transition point of the chemical reaction dominated by partial oxidation to combustion. Once the O-2/C ratio is 0.7, almost all methanol is consumed in three catalysts. Overall, the H-2 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 H-2 yield declines with rising the O-2/C ratio, whereas the measurements suggest that the H-2 production increases. For the h-BN-Pt/Al2O3 catalyst, its maximum performance, namely, the ratio of the experimental H-2 yield to the theoretical one, develops at O-2/C = 0.8 where the value is beyond 99%. However, the maximum H-2 yield of 1.66 mol (mol methanol)(-1), corresponding to the performance of 91.3%, is located at O-2/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.
Keywords:Partial oxidation of methanol (POM);Sprays;Water gas shift reaction;Methanation;Platinum (Pt) and palladium (Pd) catalysts;H-2 yield