Catalytic self-sustaining combustion of the alkanes with Pt/ZSM-5 packed bed in a microscale tube

The Effect of Catalyst Placement on the Stability of a U-Bend Catalytic Heat-Recirculating Micro-Combustor: A Numerical Investigation

This study investigates the combined effect of catalyst placement and solid thermal conductivity on the stability of a U-bend catalytic heat-recirculating micro-combustor. The CFD code ANSYS Fluent 2020 R1 was used for two-dimensional simulations of lean premixed propane/air combustion by varying the inlet gas velocity, i.e., the input power. Three configurations were compared at low (3 W/(m K)) and high (30 W/(m K)) wall thermal conductivity: (A) the configuration in which both inner and outer walls are catalyst coated; (B) only the inner wall is catalyst coated; and (C) only the outer wall is catalyst coated. Numerical results show that, at low thermal conductivity, configuration (B) exhibits the same resistance to extinction as configuration (A), whereas at high thermal conductivity, configurations (B) and (C) exhibit much lower resistance to blowout than configuration (A). Accordingly, for low-power systems, which typically lose stability via extinction and thus require low-conductive materials, an optimal catalyst placement can be the partial coating of configuration (B). Conversely, for high-power systems, which are prone to blowout and thus require high-conductivity materials, a full coating of both the inner and outer walls is needed to guarantee higher stability. To elucidate these findings, a detailed analysis of the combustion behavior of the three configurations is presented.

Catalytic combustion of methyl butanoate over HZSM-5 zeolites

Catalytic combustion technology is an exciting prospect for the removal of pollutants, especially in the field of transportation. Applying zeolites in fuel combustion has gained increasing importance in heterogeneous catalysis arising from their properties such as economical practicability and high activity. However, compared with the extensively investigated homogeneous combustion, few studies have been reported to explore the catalytic combustion of large-molecule fuels, especially for the catalytic combustion of biodiesel surrogate fuels. The purpose of this feature article is to describe the catalytic combustion of methyl butanoate (one of the biodiesel surrogate fuels) over unmodified HZSM-5 zeolites with a particular focus on the catalytic reaction mechanism. Experiments and theoretical calculations were considered here to help explain the proposed catalytic mechanism. This paper can provide new insights into the catalytic mechanism of biodiesel fuels that will guide the improvement of combustion efficiency in internal combustion engines and in the control of pollutant emissions.