Polyoxymethylene dimethyl ethers are recognized as the prospective diesel additive to decrease the pollutant emission from the light-duty vehicles, which can be polymerize form the monomer of dimethoxymethane (DMM). The industrial synthesis of DMM is mainly involved two-step process: methanol is oxidized to form the formaldehyde in fixed bed reactor and then reacted with the generated formaldehyde through acetalization in continuous stirred-tank reactor. Due to huge energy consumption, this typical synthesis route of DMM needs to be upgraded and more green routes should be determined. In this review, four state-of-the-art one-step direct synthetic routes, including two upgrading routes (methanol direct oxidation and direct dehydrogenation) and two green routes (methanol diethyl ether direct oxidation and carbon oxides direct hydrogenation), have been summarized and compared. Combination with the reaction mechanism and catalytic performance on the different catalysts, the challenges and opportunities for every synthetic route are proposed. The relationships between catalyst structure and property in different synthesis strategy are also investigated and then the suggestions of the design of catalyst are given about future research directions that efforts should be made in. Hopefully, this review can bridge the gap between newly developed catalysts and synthesis technology to realize their commercial applications in the near future.

Studies on the degradation process of waste polyethylene terephthalate (PET) have become increasingly mature, but there are relatively few studies on the separation of degradation products. The products contain many components and the separation of which is difficult. Therefore, the study on phase equilibrium thermodynamics of bis-2-hydroxyethyl terephthalate (BHET) is of great theoretical significance and practical value to provide basic data for the BHET crystallization separation. In this work, the degraded products were purified and characterized. The solubility of BHET in methanol, ethanol, ethylene glycol, water and the mixture of ethylene glycol + water were determined by static method. The experimental results were correlated with different models, such as ideal solution (IS) model, λh equation, Apelblat equation and NRTL model. Based on the van't Hoff equation, the mixing Gibbs energy, enthalpy and entropy were calculated. From this work, the basic data which can be used to guide the crystallization process of BHET were obtained, including solubility data, correlation model and thermodynamic properties.

With increasing importance attached by the international community to global climate change and the pressing energy revolution, hydrogen energy, as a clean, efficient energy carrier, can serve as an important support for the establishment of a sustainable society. The United States and countries in Europe have already formulated relevant policies and plans for the use and development of hydrogen energy. While in China, aided by the “30·60” goal, the development of the hydrogen energy, production, transmission, and storage industries is steadily advancing. This article comprehensively considers the new energy revolution and the relevant plans of various countries, focuses on the principles, development status and research hot spots, and summarizes the different green hydrogen production technologies and paths. In addition, based on its assessment of current difficulties and bottlenecks in the production of green hydrogen and the overall global hydrogen energy development status, this article discusses the development of green hydrogen technologies.

Ammonium phosphate fertilizer is the compounds containing nitrogen and phosphorus that are usually produced through the neutralization reaction of phosphoric acid and ammonia. At present, there are a variety of products, such as slurry monoammonium phosphate (MAP), diammonium phosphate (DAP), industrial grade MAP, water soluble MAP, water soluble ammonium polyphosphate (APP) and so on. After more than 60 years of development, China’s ammonium phosphate fertilizer industry has experienced the road of from scratch and from weak to strong. The successful development of the slurry MAP technology ended the history that the high concentration phosphate fertilizer cannot be produced by using the medium and low grade phosphate ore. The continuous, stable and large-scale production of DAP plant provides sufficient guarantee for DAP products in China. The development of new ammonium phosphate fertilizer products, such as industrial grade MAP, water soluble MAP, water soluble APP, provides technical support for the transformation and upgrading of phosphorus chemical enterprises. In this paper, the production methods, the development history and the latest research progress of ammonium phosphate fertilizers were reviewed.

With the development of digital products, electric vehicles and energy storage technology, electronic chemicals play an increasingly prominent role in the field of new energy such as lithium-ion batteries. Electronic chemicals have attracted extensive attention in various fields. Characteristics of high-end electronic chemicals are high purity and low impurity content, which requires a very strict separation and purification process. At present, crystallization is a key technology for their separation and purification of electronic chemicals. In this work, the representative fluorine-containing compounds in cathode and anode materials, separator and electrolyte of lithium-ion batteries are introduced. The latest technologies for the preparation and purification of four kinds of fluorine-containing battery chemicals by crystallization technology are reviewed. In addition, the research prospects and suggestions are put forward for the separation of fluorine-containing battery chemicals.

With the increasing demand for synthetic rubber, the purification of 1,3-butadiene (C₄H₆) is of great industrial significance. Herein, the successful removal of n-butene (n-C₄H₈) and iso-butene (iso-C₄H₈) from 1,3-butadiene (C₄H₆) was realized by synthesizing a novel TaOF₅^2- anion-pillared ultramicroporous material TaOFFIVE-3-Ni (also referred to as ZU-96, TaOFFIVE=TaOF₅^2-, 3=pyrazine). Single-component adsorption isotherms show that TaOFFIVE-3-Ni can achieve the exclusion of n-C₄H₈ and iso-C₄H₈ in the low pressure region (0-30 kPa), and uptake C₄H₆ with a high capacity of 92.78 cm³·cm^-3 (298 K and 100 kPa). The uptake ratio of C₄H₆/iso-C₄H₈ on TaOFFIVE-3-Ni was 20.83 (298 K and 100 kPa), which was the highest among the state-of-the-art adsorbents reported so far. With the rotation of anion and pyrazine ring, the pore size changes continuously, which makes smaller-size C₄H₆ enter the channel while larger-size n-C₄H₈ and iso-C₄H₈ are completely blocked. The excellent breakthrough performance of TaOFFIVE-3-Ni shows great potential in industrial separation of C₄ olefins. The specific adsorption binding sites within ZU-96 was further revealed through the modeling calculation.

The need for sustainable fuels has resulted in the production of renewables from a wide range of sources, in particular organic fats and oils. The use of biofuel is becoming more widespread as a result of environmental and economic considerations. Several efforts have been made to substitute fossil fuels with green fuels. Ester molecules extracted from processed animal fats and organic plant materials are considered alternatives for the use in modern engine technologies. Two different methods have been adopted for converting esters in vegetable oils/animal fats into compounds consistent with petroleum products, namely the transesterification and the hydro-processing of ester bonds for the production of biodiesel. This review paper primarily focuses on conventional and renewable biodiesel feedstocks, the catalyst used and reaction kinetics of the production process.

The knowledge of solubility of a salt in either the pure solvent or blend solvent is of great importance for studying or operating the crystallization, extraction, and distillation processes. The solubility of sodium acetate (NaAc) in four pure solvents (water, ethanol, acetic acid and 2,2,2-trifluoroethanol) and four binary solvents (water–ethanol, water-acetic acid, acetic acid–ethanol, and acetic acid-ethyl acetate) were measured by using the laser dynamic method at temperatures from 288.15 K to 338.15 K at 0.1 MPa. The results showed that the solubility of NaAc was influenced by either the solution temperature or solvent composition. The aqueous sodium acetate solution possessed the maximal solubility under the experimental conditions. The solubility of NaAc in 2,2,2-trifluoroethanol was found to be decreased with the increase of the solution temperature. While, the solubilities of NaAc in other seven solvents increased as the solution temperature was elevated. Besides, five correlation models, including the van't Hoff model, modified Apelblat model, Yaws model, λh model, and modified Apelblat-Jouyban-Acree model were used to correlate the solubility data of those sodium acetate solutions with acceptable deviation, respectively. Finally, van't Hoff analysis method was selected to analyze the change law of thermodynamic properties of a salt during the dissolution process.

Cyclohexanol is a commonly used organic compound. Currently, the most promising industrial process for synthesizing cyclohexanol, by cyclohexene hydration, suffers from a low conversion rate and difficult separation. In this paper, a three-column process for catalytic distillation applicable in the hydration of cyclohexene to cyclohexanol was established to solve these. Simulation with Aspen Plus shows that the process has good advantages, the conversion of cyclohexene reached 99.3%, and the product purity was ≥99.2%. The stable operation of the distillation system requires a good control scheme. The design of the control scheme is very important. However, at present, the reactive distillation process for cyclohexene hydration is under investigation experimentally and by steady-state simulation. Therefore, three different plant-wide control schemes were established (CS1, CS2, CS3) and the position of temperature sensitive stage was selected by using sensitivity analysis method and singular value decomposition method. The Tyreus-Luyben empirical tuning method was used to tune the controller parameters. Finally, Aspen Dynamics simulation software was used to evaluate the performance of the three control schemes. By introducing ΔF ±20% and x_ENE ±5%, comparison the changes in product purity and yield of the three different control schemes. By comparison, we can see that the control scheme CS3 has the best performance.

Enzyme-polymer conjugates are complex molecules with great practical significance. This work was designed to develop a novel enzyme-polymer conjugate by covalently coupling a zwitterionic polymer with side dimethyl chains (pID) to Candida rugosa lipase (CRL) via the reaction between the anhydrides of polymer chains with the amino groups of the enzyme. The resulting two CRL-pID conjugates with different pID grafting densities were investigated in term of the catalytic activity, stability and structural changes. In comparison with native CRL, both the CRL conjugates displayed 2.2 times higher activity than the native enzyme, and showed an increase in the maximum reaction rate (V_max) and a decrease in the Michaelis constant (K_m), thus resulting in about three-fold increases in the catalytic efficiency (k_cat/K_m). These are mainly attributed to the activation of lipase by the hydrophobic alky side chains. Moreover, the thermostability and pH tolerance of the lipase conjugates were significantly enhanced due to the stabilizing effect of the zwitterion moieties. For instance, a five-fold increase of the enzyme half-life at 50℃ for the high-pID conjugated CRL was observed. Spectroscopic studies reveal that the pID conjugation protected the enzyme in the changes in its microenvironment and conformation, well correlating with enhanced activity and stability of lipase conjugates. The findings indicate that enzyme conjugation to the zwitterionic polymer is promising for improving enzyme performance and deserves further development.

HFC-134a is a widely used environment-friendly refrigerant. At present, China is the largest producer of HFC-134a in the world. The production of HFC-134a in China mainly adopts the calcium carbide acetylene route. However, the production route has high resource and energy consumption and large waste emission, and few of the studies addressed on the environmental performance of its production process. This study quantified the environmental performance of HFC-134a production by calcium carbide route via carrying out a life cycle assessment (LCA) using the CML 2001 method. And uncertainty analysis by Monte-Carlo simulation was also carried out. The results showed that electricity had the most impact on the environment, followed by steam, hydrogen fluoride and chlorine, and the impact of direct CO₂ emissions in calcium carbide production stage on the global warming effect also could not be ignored. Therefore, the clean energy (e.g., wind, solar, biomass, and natural gas) was used to replace coal-based electricity and coal-fired steam in this study, showing considerable environmental benefits. At the same time, the use of advanced production technologies could also improve environmental benefits, and the environmental impact of the global warming category could be reduced by 4.1% via using CO₂ capture and purification technology. The Chinese database of HFC-134a production established in this study provides convenience for the relevant study of scholars. For the production of HFC-134a, this study helps to better identify the specific environmental hotspots and proposes useful ways to improve the environmental benefits.

Metal-organic frameworks (MOFs) have great potentials as adsorbents for natural gas purification. However, the trade-off between selectivity and adsorption capacity remains a challenge. Herein, we report a pillared-layer metal-organic framework Ni(HBTC)(bipy) for efficiently separating the C₃H₈/C₂H₆/CH₄ mixture. The experimental results show that the adsorption capacity of C₃H₈ and C₂H₆ on Ni(HBTC)(bipy) are as high as 6.18 and 5.85 mmol·g^-1, while only 0.93 mmol·g^-1 for CH₄ at 298 K and 100 kPa. Especially, the adsorption capacity of C₃H₈ at 5 kPa can reach an unprecedented 4.52 mmol·g^-1 and for C₂H₆ it is 1.48 mmol·g^-1 at 10 kPa. The ideal adsorbed solution theory predicted C₃H₈/CH₄ selectivity is as high as 1857.0, superior to most of the reported materials. Breakthrough experiment results indicated that material could completely separate the C₃H₈/C₂H₆/CH₄ mixture. Therefore, Ni(HBTC)(bipy) is a promising material for separation of natural gas.

There has been a strong interest in technologies suited for mining and processing of low-grade ores because of the rapid depletion of mineral resources in the world. In most cases, the extraction of copper from such raw materials is achieved by applying the leaching procedures. However, its low extraction efficiency and the long extraction period limit its large-scale commercial applications in copper recovery, even though bioleaching has been widely employed commercially for heap and dump bioleaching of secondary copper sulfide ores. Overcoming the technical challenges requires a better understanding of leaching kinetics and on-site microbial activities. Herein, this paper reviews the current status of main commercial biomining operations around the world, identifies factors that affect chalcocite dissolution both in chemical leaching and bioleaching, summarizes the related kinetic research, and concludes with a discussion of two on-site chalcocite heap leaching practices. Further, the challenges and innovations for the future development of chalcocite hydrometallurgy are presented in the end.

Solid phase extraction is widely used in sample pretreatment, concentration and analysis processes due to high selectivity and suitability for low concentration sample system. In this review, we systematically summarized and discussed the development trends of solid phase extraction by bibliometrics method. By analyzing papers output scale, the research and development direction of solid phase extraction technology is prospected. We also give an overview on current strategies of novel solid phase extraction from the separation medium and separation technology. The paper aims to describe the global research profile and the development trends of solid phase extraction, to help researchers to accurately grasp the research trend and to provide support for scientific research institutions to formulate scientific policies and strategic plans. Furthermore, the prospect of the development and application of solid phase extraction is also discussed.

Biomanufacturing, which uses renewable resources as raw materials and uses biological processes to produce energy and chemicals, has long been regarded as a production model that replaces the unsustainable fossil economy. The construction of non-natural and efficient biosynthesis routes of chemicals is an important goal of green biomanufacturing. Traditional methods that rely on experience are difficult to support the realization of this goal. However, with the rapid development of information technology, the intelligence of biomanufacturing has brought hope to achieve this goal. Retrobiosynthesis and computational enzyme design, as two of the main technologies in intelligent biomanufacturing, have developed rapidly in recent years and have made great achievements and some representative works have demonstrated the great value that the integration of the two fields may bring. To achieve the final integration of the two fields, it is necessary to examine the information, methods and tools from a bird’s-eye view, and to find a feasible idea and solution for establishing a connection point. For this purpose, this article briefly reviewed the main ideas, methods and tools of the two fields, and put forward views on how to achieve the integration of the two fields.

As a secondary energy with great commercialization potential, hydrogen energy has been widely studied due to the high calorific value, clean combustion products and various reduction methods. At present, the blueprint of hydrogen energy economy in the world is gradually taking shape. Compared with the traditional high-energy consuming methane steam reforming hydrogen production method, the electrocatalytic water splitting hydrogen production stands out among other process of hydrogen production owning to the mild reaction conditions, high-purity hydrogen generation and sustainable production process. Basing on current technical economy situation, the highly electric power cost limits the further promotion of electrocatalytic water splitting hydrogen production process. Consequently, the rational design and development of low overpotential and high stability electrocatalytic water splitting catalysts are critical toward the realization of low-cost hydrogen production technology. In this review, we summarize the existing hydrogen production methods, elaborate the reaction mechanism of the electrocatalytic water splitting reaction under acidic and alkaline conditions and the recent progress of the respective catalysts for the two half-reactions. The structure–activity relationship of the catalyst was deep-going discussed, together with the prospects of electrocatalytic water splitting and the current challenges, aiming at provide insights for electrocatalytic water splitting catalyst development and its industrial applications.

Converting polyethylene terephthalate (PET) wastes to its monomer and valuable chemicals via eco-friendly chemical method is still a challenge task. Previously, phase transfer catalysts used for alkaline hydrolysis were soluble in reaction media and hardly separated after reaction. Here, we reported several pH-responsive catalysts combined alkyl quaternary ammonium units with heteropolyacid anion for achieving stepwise product/catalyst separation and catalyst recycling. The properties of homogeneous/heterogeneous transfer behavior allow catalyst to be easily separated from reaction media by adjusting of pH value. Among them, [C₁₆H₃₃N(CH₃)₃]₃PW₁₂O₄₀ (abbreviated as [CTA]₃PW) exhibits the highest activity and the most suitable pH responsive values. Such a pH triggered switchable catalytic system not only shows good performance for depolymerization of pure PET, but also some real PET wastes such as coloured trays and PE/PET complex films could be completely degraded into terephthalic acid. Additionally, the reaction kinetics and activation energy of PET alkaline hydrolysis also studied with and without pH-responsive [CTA]₃PW.

Efficient and low-cost recycling of spent lithium iron phosphate (LiFePO₄, LFP) batteries has become an inevitable trend. In this study, an integrated closed-loop recycling strategy including isomorphic substitution leaching and solvent extraction process for spent LFP was proposed. An inexpensive FeCl₃ was used as leaching agent to directly substitute Fe²⁺ from LFP. 99% of Li can be rapidly leached in just 30 min, accompanied by 98% of FePO₄ precipitated in lixivium. The tri-n-butyl phosphate (TBP)-sulfonated kerosene (SK) system was applied to extract Li from lixivium through a twelve-stage countercurrent process containing synchronous extraction and stepwise stripping of Li⁺ and Fe³⁺. 80.81% of Li can be selectively enriched in stripping liquor containing 3.059 mol·L^-1 of Li⁺ under optimal conditions. And the Fe stripping liquor was recovered for LFP re-leaching, of which, Fe²⁺ was oxidized to Fe³⁺ by appropriate H₂O₂. Raffinate and lixivium were concentrated and entered into extraction process to accomplished close-loop recycling process. Overall, the results suggest that more than 99% of Li was recovered. FeCl₃ holding in solution was directly regenerated without any pollutant emission. The sustainable mothed would be an alternative candidate for total element recycling of spent LFP batteries with industrial potential.

A fundamental understanding of the effects of catalyst pellet structures and operation conditions on catalytic performance is crucial for the reactions limited by diffusion mass transfer. In this work, a numerical investigation has been carried out to understand the effect of catalyst pellet shapes (sphere, cylinder, trilobe and tetralobe) on the reaction-diffusion behaviors of CO methanation. The results reveal that the poly-lobe pellets with larger external specific surface area have shorter diffusion path, and thus result in higher effectiveness factors and CO conversion rates in comparison with the spherical and cylindrical pellets. The effects of operating conditions and pore structures on the trilobular catalyst pellet with high performance are further probed. Though lower temperature can contribute to larger effectiveness factors of pellets, it also brings about lower reaction rates, and pressure has little impact on the effectiveness factors of the pellets. The increase in porosity can reduce the pellet internal diffusion limitations effectively and there exists an optimal porosity for the methanation reaction. Finally, the height of the trilobular pellet is optimized under the given geometric volume, and the results demonstrate that the higher the trilobular catalyst, the better the reaction performance within the allowable mechanical strength range.

It is difficult to separate the methanol and hydrocarbons in the propylene oxide (PO) purification process due to their forming azeotrope. As for this, a novel PO separation process, in that the deionized water is employed as extractant and 1,2-propylene glycol (MPG) that is formed from the PO hydrolysis reaction is recovered, is presented in this work. The salient feature of this process is that both the non-catalyzed reactions of PO hydrolysis to form MPG and dipropylene glycol (DPG) are simultaneously considered and MPG by-product with high purity is obtained in virtue of the deionized water as reflux liquid and side take-off in MPG column. In addition, the ionic liquid (IL) extractant is screened through the conductor-like screening model for segment activity coefficient (COSMO-SAC) and the comparisons of separation efficiency between the IL and normal octane (nC₈) extractant for the separation of PO and 2-methylpentane are made. With the non-random two-liquid (NRTL) thermodynamic model, the simulation and optimization design for the full flow sheet are performed and the effects of the key operation parameters such as solvent ratio, theoretical stages, feeding stage etc. on separation efficiency are detailedly discussed. The results show that the mass purity and the mass yield of PO can be up to 99.99% and 99.0%, and the condenser duty, reboiler duty and PO loss in the process with IL extractant can be decreased by 69.66%, 30.21% and 78.86% compared to ones with nC₈. The total annual cost (TAC) calculation also suggests that the TAC would be significantly reduced if using IL in replace of nC₈ for the investigated process. The presented results would provide a useful guide for improving the quality of PO product and the economic efficiency of industrial plant.