Abstract
Catalytic partial oxidation (CPO) of logistic fuels is a promising technology for the small-scale and on-board production of syngas (H2 and CO). Rh coated monoliths can be used as catalysts that, due to Rh high activity, allow the use of reduced reactor volumes (with contact time in the order of milliseconds) and the achievement of high syngas yield. As the CPO process is globally exothermic, it can be operated in adiabatic reactors. The reaction mechanism of the CPO process involves the superposition of exothermic and endothermic reactions at the catalyst inlet. Thus, a hot spot temperature is formed, which may lead to catalyst deactivation via sintering. In this work, the effect of the flow rate on the overall performance of a CPO-reformer has been studied, using iso-octane as model fuel. The focus has been on thermal behavior. The experimental investigation consisted of iC8-CPO tests at varying total flow rates from 5 to 15 NL/min, wherein axially resolved temperature and composition measurements were performed. The increase of flow rate resulted in a progressive increase of the hot spot temperature, with partial loss of activity in the entry zone of the monolith (as evidenced by repeated reference tests of CH4-CPO); conversely, the adiabatic character of the reformer improved. A detailed modelling analysis provided the means for the interpretation of the observed results. The temperature hot spot can be limited by acting on the operating conditions of the process. However, a tradeoff is required between the stability of the catalyst and the achievement of high performances (syngas yield, reactants conversion, and reactor adiabaticity).
Highlights
IntroductionThe industrial sector (mining, manufacturing, agriculture, construction, and others) accounts for the largest share in energy consumption all around the world
Nowadays, the industrial sector accounts for the largest share in energy consumption all around the world
The criticality of obtaining a full adiabatic behavior the lab scale is well known, Lastly, it is observed that another important phenomenon was theatincrease and enlargement of and this is especially true when dealing with miniaturized systems, given the high surface-to-volume the hot spot region at increasing flow rate
Summary
The industrial sector (mining, manufacturing, agriculture, construction, and others) accounts for the largest share in energy consumption all around the world. According to IEA, the transportation sector ranks at the second position in terms of energy consumption and projections show that, in the 2015–2040 period, its demand for energy will grow more quickly than the industrial field, reaching 1%/year, 0.3% higher than the industrial rate [1] To supply this ever-increasing demand, while coping with the commitment to mitigating CO2 emissions, fuel cell and hydrogen technology can be a key player [2,3]. Flow rate is a key parameter of the reformer performance; it affects the reaction pathways, the output product yield, and the extent of heat dissipations These factors can significantly impact the thermal behavior of the reactor and, the catalyst stability. 400/7 CPSI cordierite honeycomb monolith, coated with a 2 wt% Rh/ α-Al2 O3 active phase
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