Cooperative Catalysis of Methane Oxidation through Modulating the Stabilization of PdO and Electronic Properties over Ti-Doped Alumina-Supported Palladium Catalysts

Abstract

Poor low-temperature catalytic activity and durability are the main drawbacks of palladium-based catalysts for methane combustion. Herein, stable and active PdO particles are constructed by incorporating Ti into an alumina support, which makes the catalysts exhibit satisfactory methane combustion activity. The results of comprehensive characterization reveal that an appropriate amount of Ti doping induces the optimization of electron transfer and distribution, thus contributing to the construction and stabilization of active PdO lattices. The reactive oxygen mobility is improved and the optimal PdO/Pd0 combination is achieved, thanks to the amplified PdO–support interaction. In addition, the acid–base properties are regulated and Brønsted acid sites are generated by virtue of the adjustment of electronic properties, which facilitate stabilization of PdO as well. Hence, the Ti-containing catalyst exhibits superior activity for methane oxidation at low temperatures. Notably, the activity and cyclic performance of the catalyst can be further enhanced when undergoing long-term and isothermal heat treatment under the reactant stream and methane, and it demonstrates a high performance with 90% CH4 conversion at 340 °C.

Development of a New Ternary Al2O3–HAP–Pd Catalyst for Diethyl Ether and Ethylene Production Using the Preferential Dehydration of Ethanol

“…These results indicate that the Al20-HAP80-Pd catalyst has a high catalytic activity and high stability in ethanol dehydration for the production of diethyl ether and ethylene. According to Chen et al, 56 As a result, the interaction between Pd species and the Al 2 O 3 −HAP is enhanced, leading to the improvement of the thermal stability, we think which may be one reason for the good stability of the Al20-HAP80-Pd catalyst.…”

“…These results indicate that the Al20-HAP80-Pd catalyst has a high catalytic activity and high stability in ethanol dehydration for the production of diethyl ether and ethylene. According to Chen et al, the incorporation of Pd into the lattice of Al 2 O 3 –HAP catalyst and displaces the Al 2 O 3 –HAP (calcium aluminate ion) sites to form [Al–HAP]–Pd + –O bonds, which increase the negative charge around the Al 2 O 3 –HAP. As a result, the interaction between Pd species and the Al 2 O 3 –HAP is enhanced, leading to the improvement of the thermal stability, we think which may be one reason for the good stability of the Al20-HAP80-Pd catalyst.…”

Current Progress on Methods and Technologies for Catalytic Methane Activation at Low Temperatures

“…Additionally, the TiO 2 's oxygen storing capability reduced the hysteresis between Pd reoxidation and PdO decomposition, stabilizing the PdO phase and speeding up the activation of CH 4 with a 90% conversion at 410 °C. [106] However, the poor stability of Pd/TiO 2 catalysts continues to be a major issue. [107] Recently, Xiao et al reported that a Pd catalyst supported on a reducible carrier TiO 2 via the sol-gel method and calcined 1000 °C could produce abundant Pd 2+ species, Ti 3+ , and oxygen vacancies on the surface, assisting the reoxidation of Pd 0 back to PdO and inducing a high activity toward combustion of CH 4 to CO 2 with a T 99 at 370 °C.…”

“…Additionally, the TiO 2 ’s oxygen storing capability reduced the hysteresis between Pd reoxidation and PdO decomposition, stabilizing the PdO phase and speeding up the activation of CH 4 with a 90% conversion at 410 °C. [ 106 ] However, the poor stability of Pd/TiO 2 catalysts continues to be a major issue. [ 107 ] Recently, Xiao et al.…”