No abstract

No abstract

No abstract

No abstract

To utilize a well-established infrastructure of commercial diesel fuel for hydrogen production, issues related to the process parameters are essential to resolve. In this paper, catalytic autothermal reforming of low-sulfur (wt 4 ppm) commercial diesel fuel is experimentally investigated with the focus on finding the optimum operating conditions in terms of reaction temperature, O2/C, and H2O/C and comparing them with numerical analysis to obtain maximum hydrogen yield and fuel conversion. Commercial noble metal-based Rh, supported on unpromoted CeO2 and Al2O3 powders, was used as a catalyst carrier to maximize hydrogen concentration. Catalysts were used in the dual configuration of Rh/CeO2 for oxidation reaction and Rh/Al2O3 for reforming reaction in a horizontal stainless-steel tube reactor. Parameters investigated in this study were reaction temperature, gas hourly space velocity (GHSV), and catalyst stability to achieve desired results. In an effort to reduce the overall cost of the reforming system associated with catalyst carriers, the use of unpromoted Rh/CeO2 has shown significant trade-off between cost-effectiveness and stable catalytic activity due to the high Rh reducibility on the support material and strong Rh–CeO2 interaction. Experiments showed that at an elevated reaction temperature, hydrogen concentration in the reformate can be increased at the cost of a slight reduction in fuel conversion. The maximum hydrogen concentration of 28 vol % with the corresponding CO and CH4 concentrations of 3.5 and 1.5 vol %, respectively, is achieved at optimum operating conditions of reaction temperature = 850 °C, GHSV = 5000/h, O2/C = 0.9, and H2O/C = 1.9, with a fuel conversion of 97%. Out of the used catalysts, O2-temperature-programmed oxidation has shown a high degree of carbon deposition on Rh/Al2O3 as compared to Rh/CeO2 after 24 h of on-stream reaction.

In this study, a thermodynamic analysis of the low temperature autothermal reforming (ATR) of dimethyl ether (DME) for hydrogen production was conducted. The Pd/Zn/γ-Al2O3 catalyst coated on the honeycomb cordierite ceramic was applied to catalyze the reaction, and the optimum activity temperature of this catalyst was demonstrated experimentally and through simulations to be 400 °C. Furthermore, an optimal model predictive control (MPC) strategy was designed to control the hydrogen production rate and the catalyst temperature. Experimental and simulation results indicated that the controller was automated and continuously reliable in the hydrogen production system. By establishing the state-space equations of the autothermal reformer, it can precisely control the feed rates of DME, high-purity air and deionized water. Ultimately, the hydrogen production rate can be precisely controlled when the demand curve changed from 0.09 to 0.23 mol/min, while the catalyst temperature was maintained at 400 °C, with a temporary fluctuation of 4 °C during variations of the hydrogen production rate. Therefore, the tracking performance of the hydrogen production and the anti-disturbance were satisfactory.

The objective of this study is to design an optimal model predictive control (MPC) strategy using manipulated variables to control the production of a sufficient amount of hydrogen through low temperature autothermal reforming of dimethyl ether (DME), a reforming reaction performed using PdO/ZnO/γ-Al2O3 catalysts coated on honeycomb cordierite ceramics. Experiments and simulation have verified that the optimal activity temperature of the catalyst is 400 °C, and the hydrogen volume fraction in syngas is over 43%. In the implementation of the hydrogen production system, the MPC controller can precisely determine the feed rates of DME, high-purity air, and water based on the space state equation of the reformer, to achieve the anti-disturbance of the reformer temperature. Thus, the reduction of hydrogen yield and sintering of the catalyst as a result of overheating are prevented. As the static and dynamic performance of hydrogen production exhibits excellent tracking of the setpoints, an autonomous, automated, and reliable continuous system was designed to meet the desired hydrogen demand situation. This study shows that an autonomous, automated, and reliable continuous hydrogen production reforming system can be designed to actively respond to the on-board hydrogen usage situation.