Hydrogen production for energy: An overview

With the ever increasing demand for energy to meet the needs of growth in population and improvement in the living standards in particular in developing countries, the abundant unconventional oil reserves (about 70% of total world oil), such as heavy oil, oil/tar sands and shale oil, are playing an increasingly important role in securing global energy supply. Compared with the conventional reserves unconventional oil reserves are characterized by extremely high viscosity and density, combined with complex chemistry. As a result, petroleum production from unconventional oil reserves is much more difficult and costly with more serious environmental impacts. As a key underpinning science, understanding the interfacial phenomena involved in unconventional petroleum production, such as oil liberation from host rocks, oil–water emulsions and demulsification, is critical for developing novel processes to improve oil production while reducing GHG emission and other environmental impacts at a lower operating cost. In the past decade, significant efforts and advances have been made in applying the principles of interfacial sciences to better understand complex unconventional oil-systems, while many environmental and production challenges remain. In this critical review, the recent research findings and progress in the interfacial sciences related to unconventional petroleum production are critically reviewed. In particular, the chemistry of unconventional oils, liberation mechanisms of oil from host rocks and mechanisms of emulsion stability and destabilization in unconventional oil production systems are discussed in detail. This review also seeks to summarize the current state-of-the-art characterization techniques and brings forward the challenges and opportunities for future research in this important field of physical chemistry and petroleum.

Interfacial sciences in unconventional petroleum production: from fundamentals to applications

The conversion of H2 and CO2 to liquid fuels via Power-to-Liquid (PtL) processes is gaining attention. With their higher energy densities compared to gases, the use of synthetic liquid fuels is particularly interesting in hard-to-abate sectors for which decarbonisation is difficult. However, PtL poses new challenges for the synthesis: away from syngas-based, continuously run, large-scale plants towards more flexible, small-scale concepts with direct CO2-utilisation. This review provides an overview of state of the art synthesis technologies as well as current developments and pilot plants for the most prominent PtL routes for methanol, DME and Fischer–Tropsch-fuels. It should serve as a benchmark for future concepts, guide researchers in their process development and allow a technological evaluation of alternative reactor designs. In the case of power-to-methanol and power-to-FT-fuels, several pilot plants have been realised and the first commercial scale plants are planned or already in operation. In comparison power-to-DME is much less investigated and in an earlier stage of development. For methanol the direct CO2 hydrogenation offers advantages through less by-product formation and lower heat development. However, increased water formation and lower equilibrium conversion necessitate new catalysts and reactor designs. While DME synthesis offers benefits with regards to energy efficiency, operational experience from laboratory tests and pilot plants is still missing. Furthermore, four major process routes for power-to-DME are possible, requiring additional research to determine the optimal concept. In the case of Fischer–Tropsch synthesis, catalysts for direct CO2 utilisation are still in an early stage. Consequently, today's Fischer–Tropsch-based PtL requires a shift to syngas, benefiting from advances in co-electrolysis and reverse water-gas shift reactor design.

/pdf/power-to-liquid-via-synthesis-of-methanol-dme-or-fischer-2zgn5u7uhn.pdf

Power-to-liquid via synthesis of methanol, DME or Fischer–Tropsch-fuels: a review

Carbon capture and storage (CCS) community has been struggling over the past few decades to demonstrate the economic feasibility of CO2 sequestration Nevertheless, in practice, it has only proven feasible under conditions with a market for the recovered CO2, such as in the beverage industry or enhanced oil/gas recovery The research community and industry are progressively converging to a conclusion that CO2 sequestration has severe limitations for the value proposition Alternatively, creating diverse demand markets and revenue streams for the recovered almost-pure CO2 may prevail over CO2 sequestration option and improve the economic feasibility of this climate change mitigation approach As such, research in the carbon capture and management field is seen to be shifting towards CO2 utilization, directly and indirectly, in energy and chemical industries In this paper, we have critically reviewed the literature on carbon capture, conversion, and utilization routes and assessed the progress in the research and developments in this direction Both physical and chemical CO2 utilization pathways are studied and the principles of key routes are identified The literature is also probed in addressing the process integration scenarios and the performance assessment benchmarks

Trends in CO2 conversion and utilization: A review from process systems perspective

Energy security and global warming concern are the two main driving forces for the global alcohol development that also have the effort to animate the agro-industry. Generally, alcohol and ether fuels are produced from several sources and can be produced locally. Almost all alcohol fuels have similar combustion and ignition characteristics to existing known mineral fuels. Mainly the ether fuels (MTBE and DME) are used as additives at low blending ratio to enhance the octane number and oxygen content of gasoline. The addition of alcohol and ether fuels to gasoline lead to a complete combustion due to the higher oxygen content, thereby leads to increased combustion efficiency and decreased engine emissions. The objectives of this paper are to systematically review the use of alcohols and ethers including butanol, methanol, ethanol, and fusel oil, MTBE, and DME as fuels in SI engine. Also, the current study has investigated the effects of performance (brake torque, brake power, BSFC, effective efficiency, and EGT), emissions (CO, CO2, NOx and HC) and combustion characteristics of SI engine with alcohol and ether. The increase in engine performance could be attained with an increased compression ratio along with the use of alcohol fuels which have a higher-octane value. Furthermore, alcohol and ether burn very cleanly than regular gasoline and produce lesser carbon monoxide (CO) and nitrogen oxide (NOx). On the other hand, the energy value of alcohol and ether fuels is approximately 30% lower than gasoline; thereby the specific fuel consumption (SFC) will increase simultaneously when using alcohol and ether as a fuel. Finally, this paper also discusses the impacts of alcohol on engine vibration, engine noise, and potential to be used as a gasoline octane enhancer. Alcohol can be used as a pure fuel in spark ignition engine, but it requires some modifications to the engine.

Alcohol and ether as alternative fuels in spark ignition engine: A review

Dimethyl ether (DME) is a well-known propellant and coolant, an alternative clean fuel for diesel engines which simultaneously is capable of achieving high performance and low emission of CO, NOx and particulates in its combustion. It can be produced from a variety of feed-stocks such as natural gas, coal or biomass; and also can be processed into valuable co-products such as hydrogen as a sustainable future energy. This review, which also can be counted as an extensive, pioneer review paper on this topic, presents recent developments in synthesis methods of dimethyl ether as an alternative energy while focuses on conventional processes and innovative technologies in reactor design and employed catalysts. In this context, synthesis methods are classified according to their use of raw material type as direct and indirect methods as well as other routes, since different methods need their own operating condition. Also, the available data for the selectivity to DME and its yield as a function of H2/CO and CO2 content of the feed is discussed.

Dimethyl ether: A review of technologies and production challenges

Application of palladium-based membrane technology in chemical reactions is currently focused on producing ultrapure hydrogen. Due to the environmental concerns and undesirable side effects of greenhouse gases, hydrogen has great potential as an alternative future fuel. Pd-alloy membranes have demonstrated tremendous potential for the hydrogen extraction in hydrogen-dependent reactions. Numerous studies have been done investigating the diffusion of hydrogen through palladium membranes. In this review, the ability of Pd-alloy membrane reactors in the removal of hydrogen from water gas shift, steam reforming, and dehydrogenation reactions is evaluated. This review is divided into several sections including palladium membranes, Pd-alloy membranes, composite Pd-based membranes, and their preparation methods Moreover, the hydrogen permeation rate, Sieverts’ law, Damkohler-Peclet product design parameter, and various membrane reactors will be discussed in detail. There is also an overview of the last-decade researches on Pd-based membrane reactors. Finally, some essential ideas for the improvement of future membrane technology are proposed.

Palladium membranes applications in reaction systems for hydrogen separation and purification: A review

The exploration and production of crude oil are often accompanied by water in oil emulsion (W/O) formation that can pose serious problems for downstream refinery industries. Chemical demulsification and electrostatic separation are two major techniques that are commonly used to overcome the problems associated with the formation of W/O emulsions. In this study, nano-technology was employed to facilitate the demulsification process and titania was chosen as a case study. A wide variety of nano-titania particles were synthesized by sol–gel method. The prepared samples were dispersed in a conventional chemical demulsifier to verify whether it can improve the separation process. The prepared nano-titania particles were analyzed by particle size analysis (PSA), X-ray diffraction (XRD), transmission electron microscopy (TEM), bottle test, electrostatic test, and standard IP77 method. The results specified the sample with the highest water separation performance and obviously revealed that it would effectively increase the demulsification efficiency to a value greater than 90% and it would also decrease the settling time required for efficient separation.

T. Tohidian

Papers

Dimethyl ether: A review of technologies and production challenges

Palladium membranes applications in reaction systems for hydrogen separation and purification: A review

Efficient demulsification of water-in-oil emulsion by a novel nano-titania modified chemical demulsifier

Simulation, optimization, and sensitivity analysis of a natural gas dehydration unit

Modeling and simulation of an industrial three phase trickle bed reactor responsible for the hydrogenation of 1,3-butadiene: A case study