Catalytic Combustion Characteristics Of N-butanol With Pt/ZSM-5 Particles In Micro Tubes Tubes

With the development of micro motor system,micro energy supply system are attracting more and more attention as the result of the advantages such as small volume,light weight,easy portability,high energy density and long power supply.It can provide power for micro thrusters,micro engines and micro combustors.The combustion of hydrocarbon fuel in the micro burner has become one of the most important research directions in the field of combustion.This paper focused on catalytic combustion characteristics of n-butanol including stable combustion limits,apparent activation energy,wall temperature distributions,conversion rates,the chemical dynamic model and the scale effect.The research was aimed to provide theoretical basis and reference data for the application of n-butanol as fuel in micropropulsion and micro energy power systems.The catalytic reaction of n-butanol with Pt/ZSM-5 in a 4 mm quartz tube was studied experimentally.The effects of equivalence ratio and flow rate on the catalytic effect of butyl alcohol were compared and discussed.The combustion performance,including the conversation of n-butanol with temperature,product concentration,combustion efficiency,the apparent activation energy,was acquired and analyzed.It was found out that the effect of flow rate on the catalytic combustion of butanol in the micro tube was small when the volume space velocity was less than 19080 h-1.Decrease of the equivalence ratio at a fixed flow rate yielded a higher catalytic performance toward the conversation of n-butanol,indicating that the adsorption of oxygen was the dominant factor for the reaction of n-butanol on the surface of Pt/ZSM-5.Decrease of the equivalence ratio or the flow rate both yielded a higher combustion efficiency.The apparent activation energy of the reaction of n-butanol with Pt/ZSM-5 was in the range of 110 ± 20 kJ/mol,and the apparent activation energy of the reaction was smaller at a low equivalence ratio or low flow rate.A kinetic study of butanol catalytic combustion over Pt/ZSM was investigated in a fixed-bed combustor at ambient pressure under temperatures ranging from 380 to 500 K.The Power law model and Langmuir-Hinshelwood(L-H)model(oxygen adsorption and surface reaction as the RDS)were constructed to characterize the n-butanol catalytic oxidation,the reaction rates of n-butanol were well predicted by these three models.The reaction partial orders of n-butanol and O2 were 1 and-0.23,respectively.Five pathways rate expressions were selected to predict the reaction rate for L-H model.The sum of the squared differences between the experimental data and the calculated data indicated that surface reaction,and oxygen adsorption were probably rate determining step.The reliability of the rate expressions was affirmed by comparing the experimental and calculated reaction rates.Catalytic combustion of n-butanol/air in micro tubes with different diameters was studied by numerical methods.Catalytic combustion characteristics of n-butanol at different diameters were studied.Effects of inlet velocity and equivalent ratio on the scale effect were explored,and the parameters such as the steady combustion range,the wall temperature were obtained.The steady combustion lower limit curve of tube with 2mm diameter was close to the tube with 4mm diameter,the tube with diameter of 1mm needed in a relatively large equivalence ratio to stable combustion.The maximum axis temperature and the maximum wall temperature increased with the increase of the equivalent ratio,and the maximum axis temperature increased with the increase of the inner diameter.The maximum axis temperature curves of tube between 2mm and 4mm diameter almost overlapped with the increase of the inlet velocity.However,the maximum axis temperature curve of 1mm diameter differed from the curves of 4mm diameter and 2mm diameter,the effect of velocity on scale effect was strong.