Chemical Production Processes Research Articles

Detailed kinetic analysis and modelling of the dry gasification reaction of olive kernel and lignite coal chars

The dry gasification process of solid fuels is a promising pathway to mitigate and utilize captured CO2 emissions toward syngas generation with tailored composition for several downstream energy conversion and chemical production processes. In the present work, comprehensive kinetic analysis and reaction modelling studies were carried out for olive kernel and lignite coal chars gasification reaction using pure CO2 as gasifying agent. Chars reactivity and kinetics of the gasification reactions were thoroughly examined by thermogravimetric analysis at three different heating rates and correlated with their physicochemical properties. The reactivity of olive kernel char, as determined by the mean gasification reactivity and the comprehensive gasification characteristic index, S, was almost three times higher compared to that of the lignite coal char. It was disclosed that the fixed carbon content and alkali index (AI) have a major impact on the reactivity of chars. The activation energy, Ea, estimated by three different model-free kinetic methods was ranged between 140 and 170 kJ/mol and 250–350 kJ/mol for the olive kernel and lignite coal chars, respectively. The activation energy values for the lignite coal char significantly varied with carbon conversion degree, whereas this was not the case for olive kernel char, where the activation energy remained essentially unmodified throughout the whole carbon conversion range. Finally, the combined Malek and Coats-Rendfrem method was applied to unravel the mechanism of chars-CO2 gasification reaction. It was found that the olive kernel char-CO2 gasification can be described with a 2D-diffusion mechanism function (D2) whereas the lignite coal char-CO2 gasification follows a second order chemical reaction mechanism function (F2).

Targeted chitosan nanoparticles embedded into graphene oxide functionalized with caffeic acid as a potential drug delivery system: New insight into cancer therapy

As a novel drug delivery technology, chitosan (CHI) nanoparticles are encapsulated in graphene oxide (GO) with caffeic acid (CA). The nanocarrier technique combines targeted drug delivery with molecular imaging to provide new cancer insights. Attachment of CA, an anticancer agent for controlled drug release, to functionalized graphene oxide (GON) utilizing 3-aminopropyltriethoxysilane (APTES) was followed by encapsulation of GO with folic acid (FA) attached CHI to produce this novel system. FT-IR was used to characterize and confirm the chemical production process. Brunau–Emmet–Teller (BET) analysis was used to validate multi-holes and nanometric dimensions (1–100 nm) and assess their drug administration use. Release and loading tests showed a pH dependence and implied CA hydrogen-bonding in GON. CA encapsulation and loading percentages are 86 % and 67 %, respectively. The acidic environment (pH 5.3) of tumor cells may produce a larger release of CA, and the release rate of CA maintains a constant trend, indicating the drug is released for more than a week (because the release rate has not reached zero). The proposed method provides a potential candidate for a novel drug delivery system in cancer therapy. The resulting nanohybrid system is a new way to combine biodegradable materials, that can be used in biomedical applications.

Replacement of hydrated lime by lime mud-residue from the cellulose industry in multiple-use mortars production

The pulp and paper industry increases every year in Brazil, providing an important country position in international market due to its production volume. However, because of this increasing, a large volume of wastes is generated. One of them is a lime mud, resulting from the Kraft chemical pulping production process. Thus, the aim of this study was to evaluate the replacement of hydrated lime by lime mud on laying and coating mortars production, in order to verify its feasibility for possible application in civil construction industry. The 100% hydrated lime replacement mortar reached a 28-day compressive strength of 5.84 MPa. Finally, the results obtained in the experimental program showed that the 100% hydrated lime replacement mortar by lime mud meets the normative requirements for multiple-use mortars.

Continuous Flow Chemistry and its Application in the Extraction of Natural Compounds

Abstract: Continuous flow chemistry refers to the delicate chemical production processes, without interruptions and with the best possible use. It is a practice identified as an opportune for the incorporation of the principles of Green Chemistry into economically favorable industrial processes. The purpose of this work is to verify the efficiency advantage and lower the wastage of time and materials that continuous flow extraction can bring to industries, compared to the conventional methods, such as the batch method, for bioactive compound extraction. Herein, a systematic literature review of the available research was made, and the data were collected from articles in different languages (in Portuguese, Spanish, and English), dissertations, and theses, including the Web of Science database. By collecting, analyzing, and comparing publications in which tests using different methodologies for extracting compounds were conducted, we obtained results with the acquisition of extensive information about reactors and machinery that make extraction through continuous flow chemistry viable on a laboratory scale. We observed the expansion of the exothermic synthetic step options that are not possible in batch reactors. Continuous flow chemistry proves to be very advantageous compared to other conventional methods owing to several factors, such as environmental and economical, especially because it facilitates the reuse of waste materials in industrial processes. It not only allows a relatively fast and efficient extraction but also proves to be less aggressive to the environment.

Inadvertently Generated PCBs in Consumer Products: Concentrations, Fate and Transport, and Preliminary Exposure Assessment.

Although commercial polychlorinated biphenyl (PCB) production was banned in 1979 under the Toxics Substance Control Act, inadvertent generation of PCBs through a variety of chemical production processes continues to contaminate products and waste streams. In this research, a total of 39 consumer products purchased from local and online retailer stores were analyzed for 209 PCB congeners. Inadvertent PCBs (iPCBs) were detected from seven products, and PCB-11 was the only congener detected in most of the samples, with a maximum concentration exceeding 800 ng/g. Emission of PCB-11 to air was studied from one craft foam sheet product using dynamic microchambers at 40 °C for about 120 days. PCB-11 migration from the product to house dust was also investigated. The IAQX program was then employed to estimate the emissions of PCB-11 from 10 craft foam sheets to indoor air in a 30 m3 room at 0.5 h-1 air change rate for 30 days. The predicted maximum PCB-11 concentration in the room air (156.8 ng/m3) and the measured concentration in dust (20 ng/g) were applied for the preliminary exposure assessment. The generated data from multipathway investigation in this work should be informative for further risk assessment and management for iPCBs.

A new scheme for ammonia and fertilizer generation by coal direct chemical looping hydrogen process: Concept design, parameter optimization, and performance analysis

Ammonia is a very important chemical industry product. It has a wide range of applications in refrigeration, energy, and fertilizers , and 80% of ammonia is used as a nitrogen fertilizer. China mainly produces ammonia and urea from coal gasification , which leads to difficult CO 2 capture and high energy consumption. This study proposed a new process for the production of ammonia and urea by coal direct chemical looping hydrogen production process (CDCLTU). The coal direct chemical looping hydrogen production replaces the air separation unit and water gas conversion unit of the traditional coal-to-urea process (CTU), which effectively separates and captures CO 2 and significantly reduces the energy consumption. A model of the CDCLTU was established using Aspen Plus. Parameter optimization, technoeconomic, and environmental analysis were conducted through simulations. The results showed that CDCLTU could completely replace the air separation system that the CTU relies on. Compared with the traditional process, the utilization rate of C increased from 53.46% to 67.95% in the new process. The energy consumption of CO 2 separation and capture was reduced by 97.04%. The CDCLH had a 79.7% energy efficiency in the hydrogen production process and 99% capture rate of CO 2 . The total capital investment was dropped by 41%, unit urea production cost dropped by 12.1%, and the payback period dropped from 7.5 to 3.5 years. This paper provides a new direction for clean and efficient utilization of coal resources. • Proposed a novel coal-to-urea process by chemical looping technology. • Conducted main parameters optimization and performance analysis for the new process. • The new process reduced 97.04% energy consumption of CO 2 separation and capture. • Production cost of the new process is 12.1% lower than that of the conventional process. • The new process achieved 67.95% C utilization rate and 1.39 t/t lower CO 2 emission.

Microscopic principles of chemical engineering after fossil fuels

Chemical engineering is a broad field in terms of the scope of practice but the discipline has been united by a few intellectually coherent principles. Among them, thermodynamics, reaction kinetics and transport phenomena are often considered as the cornerstones, providing support for the design and operation of diverse chemical processes for power generation and production of industrial goods such as plastics, gasoline and ammonia. Traditionally, these industrial processes use fossil fuels as the raw materials and are responsible for significant greenhouse gas emissions. As fossil-energy-based processes are deemed phasing out , development of alternative routes with renewable energy and sustainable feedstock is calling for the expansion of the knowledge base such that eco-friendly chemical processes can be quantified, controlled and optimized with high precision. This article offers some perspectives on possible engineering developments to accelerate the paradigm shift from fossil fuels to renewable energy.

Structured Supports and Catalysts: Design, Preparation, and Applications

In the field of industrial chemistry, catalysts play a fundamental role in determining the ability of chemical production processes to reach and improve productivity targets [...]

Thermodynamic modelling of hydrogen production in sorbent‐enhanced biochar‐direct chemical looping process

AbstractHydrogen (H2) has been widely considered the clean energy carrier of choice for emerging renewable energy generation technologies. However, H2 is a secondary fuel mainly derived from natural gas. Over the past decades, research on developing H2 production technology that reduces carbon emissions has gained momentum due to increasing atmospheric levels of carbon dioxide (CO2). This study proposed a new sorption‐enhanced (SE) and biochar‐direct (BD) integrated chemical looping system for hydrogen production from biomass gasification, using iron oxide as an oxygen carrier, calcium oxide (CaO) as a CO2 adsorbent, and biochar as a reducing agent. In this study, a thermodynamic model with the proposed sorbent‐enhanced biochar‐direct (SE‐BD) chemical looping hydrogen production (CLHP) process has been developed using an Aspen Plus simulator. The effect of important process parameters, including the reactor temperature, the syngas composition, and the molar feeding ratios of iron oxide/syngas, biochar/syngas, and CaO/syngas on the performance in terms of product gas composition, iron oxide conversion, H2 yield, H2 purity, and reactor heat demand has been evaluated. The simulation results show that the addition of biochar significantly enhances the overall hydrogen yield compared to the conventional CLHP process; whereas the addition of CaO‐sorbent was found to significantly improve the H2 purity. Moreover, the exothermic lime carbonation further reduced the thermal requirements of the process. In addition, this thermodynamic simulation demonstrates that the sorbent‐enhanced biochar‐direct chemical looping hydrogen production (SE‐BD‐CLHP) process can achieve a wide operating window for complete iron oxide (Fe3O4) reduction by adjusting the CaO and biochar feeding ratio.

Safety risk assessment of chemical production process based on local and global objectives

The chemical industry is a high-risk industry, and accidents such as fires and explosions occur frequently. This paper proposes a safety risk assessment model for the chemical production process based on local and global objectives to reduce and prevent accidents. The local objective is to apply the Dow Fire and Explosion Index (F&EI) method to evaluate the fire and explosion risks of each unit in the chemical production process. The global objective is to assess the global safety level of the chemical production process by establishing the index system, constructing the subjective and objective comprehensive weight model, and using the matter-element extension evaluation method. At the same time, the safety assessment model was applied and verified through a case of trimellitic anhydride production. The results show the accuracy and scientific feasibility of the safety assessment model. The model can help enterprises accurately determine the focus of prevention, improve intrinsic safety, and provide a practical tool for effectively enhancing the safety production level.

Assessment of thermodynamic parameters of the plasma chemical process for magnesium oxide production

This work are presented the calculation results of thermodynamic parameters of the reaction of magnesium fluoride decomposition by ionized water vapor with the formation of solid magnesium oxide and gaseous hydrogen fluoride at atmospheric pressure in the temperature range from room temperature to 2800◦C . The calculation of the thermodynamic parameters was carried out with the Reaction Equations software module of scientific programs HSCChemistry package. Thermodynamic analysis of magnesium fluoride MgF2 was carried out on a thermogravimetric analyzer TGA/DSC2. The thermodynamic parameters results are in good agreement with the results of thermogravimetric analysis. There were determined the optimum conditions for plasma-chemical processing of magnesium fluoride.

Concept design, technical performance, and GHG emissions analysis of petroleum coke direct chemical looping hydrogen highly integrated with gasification for methanol production process

Petroleum coke gasification for methanol production process has excellent application prospects for the clean utilization of high‑sulfur coke while limiting pollutant emissions from coke combustion. However, the process still suffers from high-energy use and a large CO2 generation caused by composition adjustment. This study proposes a novel petroleum coke chemical looping hydrogen-assisted gasification process for methanol production. Mass-energy coupling is realized by replacing the water gas shift unit with the chemical looping hydrogen unit, and the high temperature gasified gas heats the fuel reactor and in turn the feedstock. Two chemical looping hydrogen scenarios with an operating pressure of 3.0 and 0.1 MPa are considered. The methanol exergy can be increased from 484 to 1030 and 1028 MW by doubling the petroleum coke consumption through the chemical looping integration. The exergy efficiency of the new process is correspondingly increased from 51.6 to 57.1 and 55.2 % with 63.02 and 63.71 % reductions in direct CO2 emissions, as compared to the only gasification route. The calculated life cycle energy consumption and greenhouse gases emissions of the new processes are 40.02/43.84 GJ/t and 693/1055 kg CO2 eq/t, 15.14/7.05 % and 49.09/22.45 % lower than that of the benchmark process. The integration of high-pressure chemical looping technology can introduce significant technical and environmental benefits for methanol production from the petroleum coke.

Source apportionment and specific risk assessment of heavy metals in sediment: Application to the Typical Bay, China

In order to expound the spatial distribution characteristic, sources and potential ecological risk of Heavy Metals in Liaodong Bay, China, the surface sediments were collected to be analyzed from 61 sites. The research results showed that the spatial distribution characteristic of heavy metals concentration in Liaodong Bay was obviously discrepant, where the north was higher than the south, and the west was higher than the East. The ecological risk status of Liaodong Bay sediment was at the level of “Moderate Risk”. Hg and Cd were the main factors of pollution that caused the highest ecological risk. Source apportionment of heavy metal indicated that Hg and Cd in Liaodong Bay sediments might be introduced by petrochemical industry projects and offshore oil and gas development activities. Pb, Zn and Cu mainly came from the use of fossil fuels and chemical production processes, while As mainly came from agriculture.

Optimization of electrolysis and carbon capture processes for sustainable production of chemicals through Power-to-X

Abstract This contribution presents the modelling and optimization strategy of the key intermediate processes in Power-to-X: water electrolysis and carbon capture. While the water electrolysis process is set to maximize the profit provided market data, the control structure in the capture process allows the production of the stoichiometric amount of carbon dioxide for further processing to methanol. The flexible operation of electrolyzers allowed efficient conversion of renewable energy into hydrogen with minimum grid compensation (around 4%). Furthermore, the capture process showed a favourable response to the fluctuating demand of CO2, with deviations lower than 1% over the simulated period. This optimization strategy represents a viable option for Power-to-X processes to cope with the fluctuations of volatile renewable energy.

Microbial Surfactants: Bright Prospects for Innovation, New Product Categories, and Commercialization

Microbial Surfactants: Bright Prospects for Innovation, New Product Categories, and Commercialization

Parameter optimization and exergy efficiency analysis of petroleum coke-to-hydrogen by chemical looping water splitting process with CO2 capture and self-heating

The petroleum coke-to-hydrogen process is promising since the output of high-sulfur petroleum coke is increasing year by year, the pollution emissions of its combustion for power generation are serious, and the refinery needs a lot of hydrogen. Therefore, this study establishes the process model and conduct the parameter optimization of the petroleum coke direct chemical looping hydrogen production process. The optimized mass ratios of oxygen carrier (Fe2O3), steam, and air to petroleum coke are 12.71, 2.98, and 2.18; however, that are 12.71, 1.79–2.08, and 4.53–5.32 when the proportion of the reduced oxygen carrier entering steam reactor is reduced from 100% to 60–70%, which can be operated in a self-heating mode with air preheating temperature of 278.54–816.80 ℃. When the proportion is increased from 60% to 65.32% and 70%, the product exergy of hydrogen is increased from 454.58 MW to 494.92–530.36 MW with about 100% CO2 capture and the exergy efficiency is therefore increased from 59.56 to 60.75% to 62.32–63.59% and 62.65–63.91%. This paper also studies the sulfur distribution and existing forms of sulfides. Finally, this study found that the exergy efficiency of the chemical looping hydrogen process with the proportion of 65–70% is significantly higher than that of the hydrogen production process by petroleum coke gasification.

Measurement of Transport Properties of Woody Biomass Feedstock Particles Before and After Pyrolysis by Numerical Analysis of X-Ray Tomographic Reconstructions

Lignocellulosic biomass has a complex, species-specific microstructure that governs heat and mass transport during conversion processes. A quantitative understanding of the evolution of pore size and structure is critical to optimize conversion processes for biofuel and bio-based chemical production. Further, improving our understanding of the microstructure of biochar coproduct will accelerate development of its myriad applications. This work quantitatively compares the microstructural features and the anisotropic permeabilities of two woody feedstocks, red oak and Douglas fir, using X-ray computed tomography (XCT) before and after the feedstocks are subjected to pyrolysis. Quantitative analysis of the three-dimensional (3D) reconstructions allows for direct calculations of void fractions, pore size distributions and tortuosity factors. Next, 3D images are imported into an immersed boundary based finite volume solver to simulate gas flow through the porous structure and to directly calculate the principal permeabilities along longitudinal, radial, and tangential directions. The permeabilities of native biomass are seen to differ by three to four orders of magnitude in the different principal directions, but we find that this anisotropy is substantially reduced in the biochar formed during pyrolysis. The quantitative transport properties reported here enhance the ability of pyrolysis simulations to account for feedstock-specific effects and thereby provide a useful touchstone for the biorefining community.

DFT-based study on the molecular interaction of hydrochloric acid with different extractants

As an important chemical raw material, hydrochloric acid widely exists in various chemical production processes. After being used in industrial production, an acidic waste solution will be produced, creating a need to recover hydrochloric acid from the waste solution. Solvent extraction is considered to be an efficient and easy-to-operate method. This paper uses DFT theory to study the binding characteristics of different kinds of extractants and hydrochloric acid molecules. The comprehensive analysis of RDG, AIM, and ELF found that hydrogen proton transfer occurs during hydrochloric acid extraction by amine extractants, and HCl is extracted by ionic association. At the same time, alcohols, ketones, esters, and neutral phosphorus-containing species are all bonded with HCl in the form of a hydrogen bond. In addition, by studying the changes of Gibbs free energy before and after the extraction process, it was found that amines had the most potent binding force to HCl. Moreover, the binding force of TEHA to HCl is much smaller than that of other amines, which not only retains the ability to extract HCl but also makes it have excellent stripping performance. Finally, the results of the DFT calculation are verified by experiments.

Design and Analysis of Metal Oxides for CO2 Reduction Using Machine Learning, Transfer Learning, and Bayesian Optimization.

We aim to achieve resource recycling by capturing and using CO2 generated in a chemical production and disposal process. We focused on CO2 conversion to CO by the reverse water gas shift–chemical looping (RWGS-CL) reaction. This reaction proceeds in two steps (H2 + MOx ⇆ H2O + MOx–1; CO2 + MOx–1 ⇆ CO + MOx) via a metal oxide that acts as an oxygen carrier. High CO2 conversion can be achieved owing to a low H2O concentration in the second step, which causes an unwanted back reaction (H2 + CO2 ⇆ CO + H2O). However, the RWGS-CL process is difficult to control because of repeated thermochemical redox cycling, and the CO2 and H2 conversion extents vary depending on the metal oxide composition and experimental conditions. In this study, we developed metal oxides and simultaneously optimized experimental conditions to satisfy target CO2 and H2 conversion extents by using machine learning and Bayesian optimization. We used transfer learning to improve the prediction accuracy of the mathematical models by incorporating a data set and knowledge of oxygen vacancy formation energy. Furthermore, we analyzed the RWGS-CL reaction based on the prediction accuracy of each variable and the feature importance of the random forest regression model.

Modeling of methane Tri-reforming slurry bubble column reactor via differential evolution optimization method to produce syngas

Abstract Tri-reforming process of methane has been considered as an important chemical process for syngas production. The aim of this study is modeling and optimization of methane Tri-reforming slurry bubble column reactor (SBCR). A one-dimensional heterogeneous model with plug flow pattern for gas phase and an axial dispersion pattern for liquid-solid suspension has been developed for modeling of SBCR. differential evolution (DE) approach has been used for the optimization of Tri-reforming slurry reactor operating conditions. The effect of operating parameters such as inlet temperature, the ratios of O2/CH4, H2O/CH4, and CO2/CH4 on the temperature of gas, methane conversion, hydrogen production, and H2/Co ratio in the output of reactor are investigated. Methane conversion, hydrogen yield, and H2/Co ratio in optimization conditions were obtained 92%, 1.81, and 1.76, respectively. The results suggest that employment this type of reactor could be feasible and beneficial.