Direct combustion of fossils is a low efficiency process that leads to excessive carbon dioxide emissions. Highly efficient and clean combustion processes can be achieved by the use of hydrogen as fuel. Hydrogen can be produced by steam reforming of methane which is a highly endothermic process. Heat required for such endothermic process can be achieved by the use of solar energy. The literature indicates that solar reforming is restricted to high temperature generating solar technologies like solar towers and dishes due to the high heat demand of the reforming process. A novel idea of using solar parabolic troughs in conjunction with a membrane reformer has been developed which allows low temperature operation of the process due to the equilibrium shift effect. Molten salt heated in the solar parabolic trough facility (up to ~600 °C) provides heat needed for the endothermic reforming reactions. In this review, we provide critical assessment of the latest published developments in solar reforming technologies. We focus on reactor design concepts employed to couple the heat requirements of methane reforming process with concentrated solar power. The emphasis is novel, alternative routes which have potential of commercialization.

A review on solar reforming systems

On the Modeling of Steam Methane Reforming

Chemical-looping steam methane reforming (CL-SMR) is based on oxidation–reduction cycles through a solid–gas reaction with an oxygen carrier (OC) for producing high purity hydrogen or synthesis gas. In this study, Ce promoted Ni-based OC was synthesized via co-impregnation method and applied in this process. The presence of CeO2 nanoparticles in the framework of nickel oxide doped SBA-16 oxygen carrier could significantly improve the uniformity and distribution of nickel oxide nanoparticles duo to the restrictional influence of the SBA-16 framework and the strong interaction of nickel and cerium. The reaction temperature (500–750 °C), Ce loading percentage (3.9–23.3 wt. %) and Ni loading percentage (10–30 wt. %) were studied in order to investigate and optimize the catalyst structure and process temperature with maximizing the average CH4 conversion and H2 production yield in this process. The synthesized oxygen carriers were characterized by X-ray powder diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) techniques. The redox results revealed that 20Ni-11.6Ce/S16 oxygen carrier had the high catalytic activity of about 100% average CH4 conversion and 86.98% H2 production yield at reduction temperature of 700 °C.

Synthesis and characterization of cerium promoted Ni/SBA-16 oxygen carrier in cyclic chemical looping steam methane reforming

A B S T R A C T The catalytic partial oxidation of methane (CPOM) involves the interaction among methane combustion (MC), steam reforming (SR), and dry reforming (DR), and CO2 generated from MC is utilized for syngas production in DR. To evaluate the potential of CO2 utilization in CPOM for syngas production, a numerical study is carried out where CO2 is added into the feed gas and CPOM is triggered in a rhodium-based catalyst bed. Two important parameters of CO2/O2 ratio and O2/CH4 ratio (or O/C ratio) in the feed gas are taken into account. The predictions suggest that CO2 addition plays no part in MC, but it retards SR and intensifies DR. The CO2 consumption increases with CO2/O2 ratio; however, the CO2 conversion goes down. As a whole, increasing CO2 addition enhances CO formation but reduces H2 formation. The maximum syngas production is exhibited at CO2/O2 = 0.2 when the O/C ratio is 1. At a fixed CO2/O2 ratio, the maximum H2 yield and CO2 consumption are located at O/C = 1.8 and 1.0, respectively. However, the CO2 conversion monotonically decreases with increasing O/C ratio. Within the investigated range of CO2/ O2 and O/C ratios, the H2 yield and CO2 conversion in CPOM are in the ranges of approximately 0.42– 1.34 mol(mol CH4) � 1 and 10–41%, respectively.

Nasibeh Hoseini

Papers

CFD modeling of hydrogen production using steam reforming of methane in monolith reactors: Surface or volume-base reaction model?

CFD modeling of hydrogen production using steam reforming of methane in monolith reactors: Surface o