There is an immediate need to drastically reduce the emissions associated with global fossil fuel consumption in order to limit climate change. However, carbon-based materials, chemicals, and transportation fuels are predominantly made from fossil sources and currently there is no alternative source available to adequately displace them. Gas-fermenting microorganisms that fix carbon dioxide (CO2) and carbon monoxide (CO) can break this dependence as they are capable of converting gaseous carbon to fuels and chemicals. As such, the technology can utilize a wide range of feedstocks including gasified organic matter of any sort (e.g., municipal solid waste, industrial waste, biomass, and agricultural waste residues) or industrial off-gases (e.g., from steel mills or processing plants). Gas fermentation has matured to the point that large-scale production of ethanol from gas has been demonstrated by two companies. This review gives an overview of the gas fermentation process, focusing specifically on anaerobic acetogens. Applications of synthetic biology and coupling gas fermentation to additional processes are discussed in detail. Both of these strategies, demonstrated at bench-scale, have abundant potential to rapidly expand the commercial product spectrum of gas fermentation and further improve efficiencies and yields.

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Gas Fermentation—A Flexible Platform for Commercial Scale Production of Low-Carbon-Fuels and Chemicals from Waste and Renewable Feedstocks

Enhanced bioethanol dehydration by extractive and azeotropic distillation in dividing-wall columns

Throughout history, distillation has been the most widespread separation method. However, despite its simplicity and flexibility, distillation still remains very energy inefficient. Novel distillation concepts based on process intensification, can deliver major benefits, not just in terms of significantly lower energy use, but also in reducing capital investment and improving eco-efficiency. While very likely to remain the separation technology of choice for the next decades, there is no doubt that distillation technology needs to make radical changes in order to meet the demands of the energy-conscious modern society. This article aims to show that in spite of its long age, distillation technology is still young and full of breakthrough opportunities. Moreover, it provides a broad overview of the recent developments in distillation based on process intensification principles, for example heat pump assisted distillation (e.g. vapor compression or compression–resorption), heat-integrated distillation column, membrane distillation, HiGee distillation, cyclic distillation, thermally coupled distillation systems (Petlyuk), dividing-wall column, and reactive distillation. These developments as well as the future perspectives of distillation are discussed in the context of changes towards a more energy efficient and sustainable chemical process industry. Several key examples are also included to illustrate the astonishing potential of these new distillation concepts to significantly reduce the capital and operating cost at industrial scale. © 2013 Society of Chemical Industry

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Distillation technology - still young and full of breakthrough opportunities

Innovative single step bioethanol dehydration in an extractive dividing-wall column

The purification of bioethanol fuel involves an energy-intensive separation process to concentrate the diluted streams obtained in the fermentation stage and to overcome the azeotropic behavior of the ethanol-water mixture The conventional separation sequence employs three distillation columns that carry out several tasks, penalized by high-energy requirements: preconcentration of ethanol, extractive distillation, and solvent recovery To solve this problem, we propose here a novel heat-pump-assisted extractive distillation process taking place in a dividing-wall column (DWC) In this configuration, the ethanol top vapor stream of the extractive DWC is recompressed from atmospheric pressure to over 31 bar (thus to a higher temperature) and used to drive the side reboiler of the DWC, which is responsible for the water vaporization For a fair comparison with the previously reported studies, we consider here a mixture of 10 wt % ethanol (100 ktpy plant capacity) that is concentrated and dehydrated using ethylene glycol as mass-separating agent Rigorous process simulations of the proposed vapor recompression (VRC) heat-pump-assisted extractive DWC were carried out in AspenTech Aspen Plus The results show that the specific energy requirements drop from 207 kWh/kg (classic sequence) to only 124 kWh/kg ethanol (VRC-assisted extractive DWC); thus, energy savings of over 40% are possible Considering the requirements for a compressor and use of electricity in the case of the heat-pump-assisted alternative, it is possible to reduce the total annual cost by approximately 24%, despite the 29% increase of the capital expenditures, for the novel process as compared to the optimized conventional separation process

Novel Heat-Pump-Assisted Extractive Distillation for Bioethanol Purification

This article is a survey of the present-day methods of dehydration of ethanol resulting from fermentation processes. The existing separation techniques for water-ethanol mixtures of various compositions are compared, and the conditions under which each particular technique is preferable are formulated.

Bioethanol dehydration: State of the art

Densities and excess Volumes of Binary and Ternary Mixtures of N, N-Dimethyl sulfoxide, N,N-Dimethylacetamide, and N-Methyl-2-pyrrolidone at T = (293.15, 313.15)K and Atmospheric Pressure

Objectives. To improve the process of developing energy-efficient flowsheets for the distillation separation of multicomponent aqueous and organic mixtures based on a comprehensive study of the phase diagram structures, including those in the presence of additional selective substances.Methods. Thermodynamic-topological analysis of phase diagrams; modeling of phase equilibria in the AspenTech software package using the equations of local compositions: Non-Random Two Liquid and Wilson; computational experiment to determine the column parameters for separation flowsheets of model and real mixtures of various nature.Results. The fractionation conditions of the origin multicomponent mixture due to the use of sharp distillation, pre-splitting process, extractive distillation with individual and binary separating agents were revealed. The columns operation parameters and the energy consumption of the separation flowsheets ensuring the achievement of the required product quality with minimal energy consumption were determined.Conclusions. Using the original methods developed by the authors earlier and based on the generalization of the results obtained, new approaches to the synthesis of energy-efficient multicomponent mixtures separation flowsheets were proposed. The provisions that form the methodological basis for the development of flowsheets for the separation of multicomponent mixtures and supplement the standard flowsheet synthesis plan with new procedures were formulated.

Features of distillation separation of multicomponent mixtures

An Investigation of the Properties of Binary and Ternary Mixtures Containing Morpholine

По результатам вычислительного эксперимента на платформе Aspen Plus V.10.0 дан про-гноз результатов экстрактивной ректификации четырехкомпонентной смеси растворите-лей и предложены принципиальные схемы разделения с использованием разных селективных агентов в колоннах экстрактивной ректификации, работающих при разном дав-лении.

V. M. Raeva

Papers

Bioethanol dehydration: State of the art

Densities and excess Volumes of Binary and Ternary Mixtures of N, N-Dimethyl sulfoxide, N,N-Dimethylacetamide, and N-Methyl-2-pyrrolidone at T = (293.15, 313.15)K and Atmospheric Pressure

Features of distillation separation of multicomponent mixtures

An Investigation of the Properties of Binary and Ternary Mixtures Containing Morpholine

Regularities of extractive rectification of methanol—acetonitrile—tetrahydrofuran—water mixture at different pressures

V. M. Raeva

Papers

Bioethanol dehydration: State of the art

Densities and excess Volumes of Binary and Ternary Mixtures of N, N-Dimethyl sulfoxide, N,N-Dimethylacetamide, and N-Methyl-2-pyrrolidone at T = (293.15, 313.15)K and Atmospheric Pressure

Features of distillation separation of multicomponent mixtures

An Investigation of the Properties of Binary and Ternary Mixtures Containing Morpholine

Regularities of extractive rectification of methanol—acetonitrile—tetrahydrofuran—water mixture at different pressures

Densities and excess Volumes of Binary and Ternary Mixtures of N, N-Dimethyl sulfoxide, N,N-Dimethylacetamide, and N-Methyl-2-pyrrolidone at T = (293.15, 313.15)K and Atmospheric Pressure