The high power density, ease of transportation and storage and many years of development of internal combustion engine technologies have put liquid hydrocarbon fuels at a privileged position in our energy mix. Therefore processes that use renewable energy sources to produce liquid hydrocarbon fuels from H2O and CO2 are of crucial importance. Concentrated Solar Power (CSP) can be employed as the only energy source for the renewable production of hydrogen from water either indirectly, e.g. by supplying the electricity for electrolysis, or directly by supplying the necessary heat for thermochemically producing hydrogen. Among the various thermochemical cycles tested so far for CSP-driven hydrogen production via water splitting (WS), those based on redox-pair oxide systems, are directly adaptable to carbon dioxide splitting (CDS) and/or combined CO2/H2O splitting for the production of CO or syngas, respectively. The acknowledgement of this fact has recently revived the interest of the scientific community on such technologies. The current article presents the development, evolution and current status of CSP-aided syngas production via such redox-pair-based thermochemical cycles. At first the various redox oxide material compositions tested for water/carbon dioxide splitting are presented and their redox chemistries are discussed. Then the selection of suitable solar reactors is addressed in conjunction with the boundary conditions imposed by the redox systems as well as the heat demands, technical peculiarities and requirements of the cycle steps. The various solar reactor concepts proposed and employed for such reactions and their current status of development are presented. Finally, topics where further work is needed for commercialization of the technology are identified and discussed.

A review on solar thermal syngas production via redox pair-based water/carbon dioxide splitting thermochemical cycles

Hydrogen is an attractive energy carrier due to its potentially high energy efficiency and low generation of pollutants, which can be used for transportation and stationary power generation. However, hydrogen is not readily available in sufficient quantities and the production cost is still high. Steam methane reforming (SMR) process is now the most widely used technology for H 2 production, but this process is complex and cannot get thorough carbon capture. Hydrogen production using chemical looping technology has received a great deal of attention in recent years because it can produce hydrogen with higher process efficiency and can capture carbon dioxide. Many researchers have carried out intensive research work on the hydrogen production processes using chemical looping technology. Based on the previous studies stated in the literature, the authors try to give an overview on the recent advances of two categories, chemical looping reforming (CLR) and chemical looping hydrogen production (CLH) processes. Besides, the characteristics of the processes are pointed out based on the comparison with the conventional SMR process. The existing technical problems and the aspects of future research of each approach are also summarized.

Review of hydrogen production using chemical-looping technology

Coke formation during the thermolysis of petroleum residua is postulated to occur by a mechanism that involve the liquid-liquid phase separation of reacted asphaltene to form a phase that is been in abstractable hydrogen. This mechanism provide the basis of a model that quantitatively describe the kinetics for the thermolysis of ColD Lake vacuum residuum and its deasphalted oil in a open fuse reactor at 400°C. The previously unreacted asphaltene were found to be the fraction with the highest rate of thermal reaction but with the least extend of reaction. Further evidence of the liquid-liquid phase separation was the observation of spherical particle of liquid crystalline coke and the preferential conversion of the most associated asphatene to coke

A phase separation kinetic model for coke formation

High temperature CO2 sorbents and their application for hydrogen production by sorption enhanced steam reforming process

Renewable alternative energy sources are getting more attention due to the depleting nature of non-renewable fossil fuels. Increasing global warming, caused by the combustion of fossil fuels, triggered the intense research in finding out better energy options with low emission. Among the potential energy options, hydrogen is a clean fuel candidate as it simply produces water as byproducts when burning. Hydrogen can be generated from different renewable sources and Asia is one of the continents which is rich in renewable energy resources. The resources, safety parameters, public acceptability, and proper government incentives are the major factors affecting the implementation of hydrogen as an economical energy source in Asian countries. The present review deals with the necessity of employing hydrogen as an alternative fuel, its production paths, storage issues, transportation and the available sources. Special emphasis has been given to the discussion of renewable hydrogen economy in some Asian countries like, Japan, Korea, China, India and Malaysia. The challenges in the execution of hydrogen as an economical fuel in Asia are also highlighted.

Renewable hydrogen economy in Asia – Opportunities and challenges: An overview

Reaction kinetics of reduction and oxidation of metal oxides for hydrogen production

Hydrogen production from two-step steam methane reforming in a fluidized bed reactor

The chemical-looping hydrogen generation (CLH) system consists of reduction of metal oxide and water decomposition by oxidizing reduced metal oxide. In the present study, water decomposition by the reduction and oxidation of metal oxide (CuO) was conducted in a thermogravimetric analysis (TGA) system for the CLH process. The particles are reduced completely in an atmosphere of synthesis gas (H2 + CO), and the fully reduced particles decompose water to produce 3.7 L of H2 per kilogram of metal oxide. The particles prepared by the impregnation exhibits better reactivity than those by coprecipitation and the solid phase method, and the particles supported on Al2O3 exhibit better reactivity than those on SiO2. Based on the TGA, the reduction and oxidation of CuO/Al2O3 prepared via impregnation are characterized by the kinetic equations from the solid-state reaction rate models. The phase-controlled-boundary model was successfully applied to predict the initial stages of reduction and oxidation of the metal ox...

Kang Seok Go

Papers

Reaction kinetics of reduction and oxidation of metal oxides for hydrogen production

Hydrogen production from two-step steam methane reforming in a fluidized bed reactor

Thermogravimetric Analysis of Copper Oxide for Chemical-Looping Hydrogen Generation

Effect of surface properties controlled by Ce addition on CO2 methanation over Ni/Ce/Al2O3 catalyst

Characteristics of slurry-phase hydrocracking for vacuum residue with reaction temperature and concentrations of MoS2 dispersed catalysts