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The use of fossil resources has lead to great increase in concentration of carbon dioxide (CO2) in the atmosphere beyond sustainable limits, which causes environmental issues such as greenhouse gas effect, climate change and extreme weather events and threats the human life. Thus, several researches have been focused on mitigate this problem. Possible strategies involve implementing technologies of carbon capture storage and utilization. Among them, integrated processes for carbon dioxide capture and its conversion into value-added products have gained attention. Carbon dioxide hydrogenation is among the most developed technologies for its conversion, but requires an external hydrogen (H2) source. Since the conversion of carbon dioxide is highly energy-demanding, assessing its overall process sustainability requires a comprehensive study on the whole system, including its raw material sources (carbon dioxide and hydrogen). Thus, this work proposes a multi-criteria framework to select suitable sources of carbon dioxide and hydrogen to be used in the conversion of carbon dioxide. Potential sources of carbon dioxide (from power plants to ethanol fermentation) and hydrogen (from dedicated production to by-product hydrogen) were evaluated considering environmental, economic, and technical aspects associated with the usage of each source. The Technique of Order Preference Similarity to the Ideal Solution (TOPSIS) is the multi-criteria decision analysis method used to aggregate the criteria and to rank each source individually and further in a pair-wise assessment to identify potential synergic combinations between carbon dioxide and hydrogen sources. Results suggested that using carbon dioxide from natural gas steam reforming, iron and steel industries, ethylene oxide and other high concentration point sources may be the ideal choice for sustainability. The analysis also indicated that hydrogen may be more sustainable if it is a process by-product or is produced by low-cost wind-powered electrolysis. It is important to consider that the analysis is based on several specific data inputs and assumptions, and that a lower score does not mean that the source is not worth investing in.

Direct hydrogenation of carbon dioxide (CO2) to formic acid is unfavorable thermodynamically, which makes its production limited. In this study, a thermodynamic analysis of CO2 hydrogenation to binary product systems of methanol and formic acid promoted by ionic liquid (IL) (1-ethyl-2,3-dimethylimidazolium nitrite, ([Edmim][NO2]) is presented. The analysis is conducted in Aspen Plus using the Gibbs energy minimization approach combined with a vapor–liquid equilibrium (VLE) for the solvation of CO2 in IL. It is demonstrated that solvating CO2 in ILs is an attractive alternative to overcome the thermodynamic difficulty associated with the product yield, especially formic acid. The [Edmim][NO2] promoted system is very effective for the simultaneous production of formic acid and methanol at 25 °C and 17 bar with a yield of 35% formic acid and 30% methanol at a CO2/H2/IL ratio of 1/2/2. The results show a marked improvement in the yield of formic acid to other previously conducted studies on formic acid production.

Glycerol from biodiesel is a potential raw material for synthesis of several products with high added value. The world demand and the market value of these products are important information for defining the best investment for the implantation of a biorefinery. The information is available on websites of social associations, production companies and market consulting companies and can be mined, free of charge. The International Trade Center (ITC), with information on world trade and websites linked to the foreign trade agencies of every country, such as Comex Stat, in Brazil, are relevant search sources. In this context, this work presents procedures and search techniques for prospecting such information. Such a procedure is illustrated through a case study for which a search of market parameters for glycerol and its derivatives was carried out for use in the process design and economic evaluation of an industrial plant. It was found that crude glycerol had a market price close to US$ 170/ton, in 2019. Among its derivatives, acrylic acid, acrylonitrile and 1,3-propanediol have great potential for the development of new processes, within the scope of a biorefinery. Industrially, acrylic acid (US$ 1100/ton) and acrylonitrile (US$ 1500/ton) are produced from propene (US$ 880/ ton) and 1,3-propanediol (US $ 2000/ton) comes from glucose (US$ 460/t) or ethylene oxide (US$ 1200/t), which encourages the development of new sustainable processes.

New synthetic routes to acetic acid production using CO2 have been studied, such as methanol hydrocarboxylation, reaction of methane with CO2, lignin with CO2 and CO2 hydrogenation. They represent a significant progress in synthetic chemistry, with the novel approach to acetic acid production and CO2 transformation. These innovative routes can replace fossil raw materials by CO2, additionally promote CO2.abatement. This study presents an assessment of acetic acid production from CO2 and identification of the most promising route by a multicriteria decision analysis, including process demand and characteristics, and a shortcut exergy criterion. Methanol hydrocarboxylation has demonstrated to be the best one. The process was designed based on hierarchical approach process synthesis in Aspen Plus simulator to verify its technical feasibility. An exergetic analysis was carried out in the proposed process design to evaluate thermodynamic inefficiencies. The gas recompression and the gas separation system presented the highest exergy destruction, in which possible process intensification or enhancements potentially improve the process.

Carbon dioxide can be used as feedstock to produce chemicals. It represents a stimulating defiance to manufacture novel cost competitive materials with less environmental impact, besides to investigate new opportunities for catalysts and industrial chemistry. The contribution of carbon dioxide conversion goes beyond lowering global warming, by reducing fossil resource depletion or even yielding more benign production pathways. Albeit promising, the literature data regarding the quantity of energy needed to convert carbon dioxide into chemicals is limited and narrowed to the most studied processes and products. In order to understand and model the formation of species using carbon dioxide as raw material, some basic thermodynamic data are needed. The development of detailed reaction schemes in the field is also scarce. To enhance and further complete the database of the products obtained from carbon dioxide, this study investigates different procedures to estimate the basic thermodynamic properties of the reactants and products of these reactions. To date various methods have been developed and introduced to determine the gas-phase standard enthalpies of formation and Gibbs energy. Among them, group additivity and semi-empirical methods are widely employed due to their accuracy and effort time for implementation compared to more rigorous methods. Semi empirical quantum-chemistry methods were compared with group additivity methods. Available literature data were used to select the best method for property estimation of the whole set of species, whereby produced from carbon dioxide. The products from carbon dioxide were categorized in sixteen chemical classes, the reaction enthalpy for the direct route to manufacture the products were assessed and indicate a large difference among the classes. The results of this investigation show that semi empirical quantum-chemistry methods revealed to be more accurate for the studied species; additionally, the method demonstrates robustness in estimating the properties. Together, these results provide important insights into the thermodynamics of carbon dioxide related products.

This paper explores the production of two intermediate chemicals with wide uses in industrial scale. The CO2 hydrogenation using ammonia as an alkyl base produces ammonium formate and carbamate suitable for formic acid and urea synthesis. For this, an investigative simulation study was carried out to explore the possible operating conditions for each product. The given results pointed out that 50 °C and 1 bar favour the production of carbamate, obtaining 99% of yield and decrease formate one to less than 1%. However, low temperature (10 °C) and high pressure (50 bar) promote the formate yield to 81% and smaller quantities of carbamate, around 8%. CO2 conversion is around 99% at 50 °C and 1 bar, when H2O/NH3 ratio is 2.

Several international agreements, focused on regulating greenhouse gases emissions in the atmosphere, were created due to the growing concern about the climate change due to human action. The carbon dioxide (CO2) emissions account for more than 70% of the total greenhouse gases emissions; among the CO2 emitting sectors, electricity generation accounts for 25% of the global emissions. CO2 emissions from Brazilian power plants motivated their mapping, a method was proposed to performance a local market analysis for potential products from CO2 chemical conversion. The forecast behavior of this market for 2030 was also calculated. Among the studied products, methanol, polycarbonates, formic acid and acetaldehyde are the most promising for local manufacture. The States of Sao Paulo, Parana, Amazonas, Bahia, Rio Grande do Sul and Santa Catarina are the most promising regions in terms of potential of CO2 utilization.

The production of chemicals and fuels from carbon dioxide can lead to a sustainable low carbon pathway for the chemical industry. The use of carbon dioxide as feedstock poses a commercially challenge, which is to develop alternative raw materials at lower cost and also to lower manufacturing impacts. Many products can be developed from carbon dioxide as raw material through carboxylation or hydrogenation reactions. In carbon capture and utilization (CCU), a particular carbon dioxide utilization technology shows specific aspects for emission reduction potential, intrinsic thermodynamic restrictions and commercial maturity level. Each product brings some advantages and penalties, making it therefore important to define some criteria to evaluate and to choose the most attractive products. This study proposes an exploratory screening procedure to identify promising chemical targets to be produced from carbon dioxide conversion among a large number of candidates. In the methodological framework, a systematic literature search is conducted to point out important criteria to take into account, followed by the selection of a multicriteria decision analysis tool that best fits to the data under study. The final step applies a three-level screening, in which important factors, such as thermodynamic data, market size and growth, price of product and carbon dioxide utilization ratio are considered. The results of the evaluation demonstrate that dimethyl carbonate, acetic acid and dimethyl ether are promising products for further study. Such a procedure would accelerate the development into the chemical design process of novel CCU technologies.

In petroleum refineries, water is used in desalting units to remove the salt contained in crude oil. Typically, 7 % of the volume of hot crude oil is water, forming a water-and-oil emulsion. The emulsion flows between two electrodes and is subjected to an electric field. The electrical forces promote the coalescence of small droplets of water dispersed in crude oil, and these form bigger droplets. This paper calculates the forces acting on the droplets, highlighting particularly the mechanisms proposed for droplet―droplet coalescence under the influence of an applied electric field. Moreover, a model is developed in order to calculate the displacement speed of the droplets and the time between droplet collisions. Thus, it is possible to simulate and optimize the process by changing the operational variables (temperature, electrical field, and water quantity). The main advantage of this study is to show that it is feasible to increase the volume of water recycled in desalting processes, thus reducing the use of freshwater and the generation of liquid effluents in refineries.

Water is used in petroleum desalting units to dilute and remove the salted water droplets that the crude oil contains. The basic processes promote the coalescence of small droplets of conducting water dispersed in a crude oil emulsion. In order to make separation easier, the emulsion is distributed horizontally between two electrodes and subjected to an electrical field, which generates an attractive force among the droplets, promoting coalescence phenomena and further sedimentation. The main purpose of this study is to reduce the demand of fresh water and the liquid effluent generation in refineries. This paper presents a new model developed in order to calculate the droplets velocity by using the balance of the acting forces. The model is able to determine the droplets trajectory in order to define if they can be separated from the continuous phase. Besides the deterministic approaches based on traditional equations, the model uses also the concept of cellular automata. Thus it is possible to solve the problem in a stochastic way and to show visually the sequence of droplets collisions and coalescence phenomena. This methodology enables to calculate the amount of water that can be separated of the emulsion for a number of different operating conditions and then to optimize the process. Comparisons between the obtained results by the developed model and the operational performance of a real desalting unit are carried out. A good accuracy is observed, which shows that the real process is very well represented by the developed model.