Key Industrial Processes Research Articles

Understanding pore features of pillar-layered MOFs on one-step C2H4 purification from C2H6/C2H4 mixtures

Purification of ethylene from ethane through adsorption separation is a key industrial process in present chemical field, since the similar physical properties of both C2H4 and C2H6 that makes them difficult to separate. Therefore, constructing C2H6-selective adsorbents and clarifying its structure–activity relationship is a very difficult undertaking. In this study, 3D pillar-layered metal organic frameworks (MMOF-kgm (M = Zn, Co, Ni) and NiMOF-sql) with different topologies, kagome and square lattice, were constructed by using the cheap ligands (1,4-benzenedicarboxylic acid and triethylenediamine). The effect of pore features on C2H6/C2H4 separation performance and the separation mechanism were systematically investigated by the above two isomeric MOFs. In particular, NiMOF-kgm with kagome topology provides narrower triangular pore shows notably adsorption of C2H6 over C2H4, which is validated by gas adsorption, IAST selectivity and breakthrough measurements. The selective adsorption mechanisms of MOF with kagome topology were further revealed through DFT calculations. This study provides in-depth insights into optimizing the pore structure of MOFs to enhance C2H6/C2H4 separation performance, offering new design strategies for developing efficient materials for ethane-selective adsorbent for one-step ethylene purification.

Rotating Disk Electrode Studies of Benzaldehyde Oxidation on Group Ib Metals

Water electrolysis is a green means of producing hydrogen gas to be used as a fuel or reactant in key industrial processes such as ammonia production. The conventional system of oxygen evolution (OER) and hydrogen evolution (HER) suffers from slow kinetics at the anode and a high cell voltage limited by thermodynamics. One solution is to replace OER with another reaction such as an organic oxidation reaction that has a lower equilibrium potential and produces a valuable organic byproduct at the anode. Recent work has demonstrated that biomass-derived aldehydes such as furfural and 5-hydroxymethylfurfural can be selectively oxidized to their corresponding carboxylates and H2 on Cu-based anodes at low potentials (~0.1 VRHE) in alkaline media. In alkaline media, a hydroxide ion adds to the carbonyl carbon of an aldehyde molecule forming a gem diolate in solution phase. It is argued that dehydrogenation becomes more facile due to the weaker C-H bond of the gem diolate compared to the aldehyde form of the molecule. This may enable oxidation without the need for coadsorbed-OH. Additionally, aldehyde oxidation is only active on Au, Ag, and Cu electrodes at higher pHs.The aim of this work is to identify the conditions under which low potential oxidation of aldehydes and high anodic Faradaic efficiency to H2 occurs, namely, electrode material and applied potential. To avoid polymerization side reactions of furans in alkaline media, we studied benzaldehyde as a model compound which has also been shown to exhibit low potential oxidation and anodic H2. The activity (rate of aldehyde consumption) and selectivity (to anodic H2 versus H2O) were compared for the group Ib metals (Au, Ag, Cu), each of which demonstrates a relatively early onset potential (<0.4 VRHE) and generates anodic H2 at certain potentials. Rotating disk electrode studies with Koutecky-Levich analysis were conducted to separate mass transfer effects from kinetic current to compare the intrinsic activity of each electrode. Additionally, the average number electrons transferred per aldehyde molecule consumed was estimated from Koutecky-Levich analysis; the one-electron pathway combines the aldehyde hydrogens to H2 while the two-electron pathway requires an additional electron per aldehyde molecule to oxidize the hydrogen from the surface to form H2O. Rotating ring disk electrode studies were used to further validate the anodic H2 generation as a Pt ring was still able to oxidize H2 despite the presence of benzaldehyde. This was used as an additional means of estimating the selectivity to H2 as a function of potential.CVs for benzaldehyde oxidation on each metal are shown in Figure a. Peak current followed the order of Au > Ag >> Cu. Au reached a mass transfer limiting current, and Ag also showed an RPM dependence but did not reach full mass transfer limitations. Cu was the least active and did not show any mass transfer dependence. On the other hand, Cu has the earliest onset potential followed by Ag then Au. The average number of electrons transferred per aldehyde molecule according to RRDE measurements is shown in Figure b, where one electron represents H2 and two electrons represents H-oxidation to H2O. Cu had 100% selectivity to H2 over its entire potential window of activity (up to 0.45 VRHE). Au and Ag have high selectivity to H2 at low potentials but decreases to near zero H2 production in the range of 0.6-0.8 VRHE; the decrease in selectivity to H2 on Ag occurs slightly earlier than Au (~0.1 V). H2 selectivity is related to the inability of each metal to oxidize H to H2O at low potentials. Figure 1

One-Pot Synthesis of CHA/ERI-Type Zeolite Intergrowth from a Single Multiselective Organic Structure-Directing Agent.

We report the one-pot synthesis of a chabazite (CHA)/erionite (ERI)-type zeolite intergrowth structure characterized by adjustable extents of intergrowth enrichment and Si/Al molar ratios. This method utilizes readily synthesizable 6-azaspiro[5.6]dodecan-6-ium as the exclusive organic structure-directing agent (OSDA) within a potassium-dominant environment. High-throughput simulations were used to accurately determine the templating energy and molecular shape, facilitating the selection of an optimally biselective OSDA from among thousands of prospective candidates. The coexistence of the crystal phases, forming a distinct structure comprising disk-like CHA regions bridged by ERI-rich pillars, was corroborated via rigorous powder X-ray diffraction and integrated differential-phase contrast scanning transmission electron microscopy (iDPC S/TEM) analyses. iDPC S/TEM imaging further revealed the presence of single offretite layers dispersed within the ERI phase. The ratio of crystal phases between CHA and ERI in this type of intergrowth could be varied systematically by changing both the OSDA/Si and K/Si ratios. Two intergrown zeolite samples with different Si/Al molar ratios were tested for the selective catalytic reduction (SCR) of NOx with NH3, showing competitive catalytic performance and hydrothermal stability compared to that of the industry-standard commercial NH3-SCR catalyst, Cu-SSZ-13, prevalent in automotive applications. Collectively, this work underscores the potential of our approach for the synthesis and optimization of adjustable intergrown zeolite structures, offering competitive alternatives for key industrial processes.

Data-driven sensor delay estimation in industrial processes using multivariate projection methods

A key step in preparing industrial data for multivariate statistical modelling of (batch-)continuous processes is the estimation of sensor delays along the production line, to use as a correction for understanding relationships between them. Without such a correction, the measurements collected from the sensors do not all relate to the same portion of material travelling through the plant, which is where from a physical point of view the correlations are expected to arise from. Most methods to do these corrections currently reported in literature are limited in that they optimize only correlations bivariately between the different sensors, despite the eventual goal of being understood as a multivariate process model. This work proposes several methods for multivariate sensor delay estimation, based on multivariate projection methods, and critically investigates these using simulated and empirical process data from two industrial facilities. The objective is to provide more clarity on if, how, and why taking into account these multivariate correlations using such projection methods is beneficial. One of the proposed methods, named PLS-SEQ, was shown to outperform bivariate sensor delay estimation, which is regarded as benchmark method in this work, for all datasets. The average reduction in delay estimation error achieved by using PLS-SEQ is between 6% and 64%. The other newly proposed multivariate projection-based methods did not show such unanimous improvement in accuracy, but helped identifying the presence of sensor clusters in industrial data as a novel key challenge for sensor delay estimation. The presented results illustrate that projection-based multivariate methods, in particular the newly proposed method PLS-SEQ, show promising potential for sensor delay estimation, outperforming the bivariate sensor delay estimation methods used as benchmark. Ultimately, using these methods can improve the predictive and descriptive quality of statistical models for key industrial processes.

Liquid-diffusion electrode with core-shell structured mixed metal oxide catalyst for near-zero polarization in chlor-alkali electrolysis

Chlor-alkali electrolysis is a key industrial process for the production of chlorine gas, caustic soda, and hydrogen fuels. Here, we demonstrate that a Ti foam electrode, which has a diffusion layer of liquid reactant, deposited with a thin layer of core/shell-structured mixed metal oxide nanoparticles enables almost zero polarization in the range of hundreds of mA cm−2 towards the chlorine evolution reaction (CER), using noble-metals 20 times lower than commercial electrode. The fast charge-transfer kinetics induce near-zero overpotential at low current densities, while the high mass transport rates aided by porous channels lead to unprecedentedly high CER performance (LSV derived overpotentials of 9 and 44 mV at 10 and 500 mA cm−2 with Faradaic efficiency of 99.1% and 86.1% in 5.0 M NaCl). Under practical chlor-alkali process conditions, the RNTO/Ti foam exhibited remarkable performance as a bifunctional electrode for CER and hydrogen evolution reaction (HER) with overpotential of 11 mV for HER.

Photo-thermo semi-hydrogenation of acetylene on Pd1/TiO2 single-atom catalyst

Semi-hydrogenation of acetylene in excess ethylene is a key industrial process for ethylene purification. Supported Pd catalysts have attracted most attention due to their superior intrinsic activity but often suffer from low selectivity. Pd single-atom catalysts (SACs) are promising to significantly improve the selectivity, but the activity needs to be improved and the feasible preparation of Pd SACs remains a grand challenge. Here, we report a simple strategy to construct Pd1/TiO2 SACs by selectively encapsulating the co-existed small amount of Pd nanoclusters/nanoparticles based on their different strong metal-support interaction (SMSI) occurrence conditions. In addition, photo-thermo catalysis has been applied to this process where a much-improved catalytic activity was obtained. Detailed characterization combined with DFT calculation suggests that photo-induced electrons transferred from TiO2 to the adjacent Pd atoms facilitate the activation of acetylene. This work offers an opportunity to develop highly stable Pd SACs for efficient catalytic semi-hydrogenation process.

Design of carbon supports for metal-catalyzed acetylene hydrochlorination

For decades, carbons have been the support of choice in acetylene hydrochlorination, a key industrial process for polyvinyl chloride manufacture. However, no unequivocal design criteria could be established to date, due to the complex interplay between the carbon host and the metal nanostructure. Herein, we disentangle the roles of carbon in determining activity and stability of platinum-, ruthenium-, and gold-based hydrochlorination catalysts and derive descriptors for optimal host design, by systematically varying the porous properties and surface functionalization of carbon, while preserving the active metal sites. The acetylene adsorption capacity is identified as central activity descriptor, while the density of acidic oxygen sites determines the coking tendency and thus catalyst stability. With this understanding, a platinum single-atom catalyst is developed with stable catalytic performance under two-fold accelerated deactivation conditions compared to the state-of-the-art system, marking a step ahead towards sustainable PVC production.

Strategic Challenges of Human Resources Allocation in Industry 4.0

The emergence of the fourth industrial revolution (Industry 4.0, hereinafter I 4.0) has led to an entirely fresh approach to production, helping to enhance the key industrial processes and therefore increase the growth of labor productivity and competitiveness. Simultaneously, I 4.0 compels changes in the organization of work and influences the lives of employees. The paper intends to construct a model for predicting the allocation of human resources in the sectors of the national economy of the Czech Republic in connection with I 4.0. The model used in this research visualizes the shift of labor in the economic sectors of the Czech Republic from the year 2013 to the following years in the near future. The main contribution of this article is to show the growth of employment in the high-tech services sector, which will have an ascending trend.

Molecular Simulation of Electrode-Solution Interfaces.

Many key industrial processes, from electricity production, conversion, and storage to electrocatalysis or electrochemistry in general, rely on physical mechanisms occurring at the interface between a metallic electrode and an electrolyte solution, summarized by the concept of an electric double layer, with the accumulation/depletion of electrons on the metal side and of ions on the liquid side. While electrostatic interactions play an essential role in the structure, thermodynamics, dynamics, and reactivity of electrode-electrolyte interfaces, these properties also crucially depend on the nature of the ions and solvent, as well as that of the metal itself. Such interfaces pose many challenges for modeling because they are a place where quantum chemistry meets statistical physics. In the present review, we explore the recent advances in the description and understanding of electrode-electrolyte interfaces with classical molecular simulations, with a focus on planar interfaces and solvent-based liquids, from pure solvent to water-in-salt electrolytes.

Novel Bimetallic Cu–Pd Nanoparticles as Highly Active Low-Temperature WGS Catalysts

Water gas shift (WGS) reaction is a key industrial process to produce hydrogen from CO and H2O. However, conventional Cu-based WGS catalysts are easily deactivated by sulfur compounds, which are ubiquitous in syngas. Cu–Pd nanoparticles of size 8–10 nm were synthesized as a function of the Cu/Pd ratios and investigated as promising sulfur-tolerant WGS catalysts. Significant improvement in the WGS activity was observed in the Cu–Pd catalysts after calcination at 800 °C in air. Pd addition enhanced the reducibility of CuO and Cu0 dispersion and limited the formation of CuAl2O4 spinel during calcination at 800 °C. The additional reducible and catalytically active CuO species was generated by the Cu migration from the CuO shell covering the Cu–Pd nanoparticles onto the γ-Al2O3 support during the 800 °C calcination. The optimal Cu–Pd catalyst characterized by the CuO/CuAl2O4 ratio of 2.37 showed the highest WGS activity, thermal stability, and sulfur tolerance among all Cu-based catalysts reported in this study.

Support Effect of the Fe/BN Catalyst on Fischer–Tropsch Performances: Role of the Surface B–O Defect

BN nanosheets (BN) have drawn great attention in heterogeneous catalysis recently, and their defects have a profound effect on the key performance of the catalyst, but it has been overseen and little addressed. Here, three Fe/BN nanosheet (Fe/BN) catalysts were prepared BN with varied B–O surface defects. Fischer–Tropsch synthesis, a key industrial process, was taken as an example. It is found that the rich B–O defects not only resulted in decreased crystal size and low crystallinity of the Fe2O3 but also showed enhanced interaction with the active component and support. As a consequence, the three Fe/BN catalysts showed a dramatic difference in catalytic performance. Our studies reported here could be a guide for the rational design of the highly efficient hydrogenation BN-based catalyst.

The impact of nanocrystallite size and shape on phase transformation: Application to the boehmite/alumina transformation

The thermal activation of oxyhydroxides is a key industrial process in preparing oxide materials. When dealing with nanoparticles, the phase transition properties are drastically modified. By preparing size- and shape-controlled boehmite nanoparticles, we demonstrate that the transformation temperature into γ-alumina is significantly altered. Rhombus crystallites were obtained from boehmite precipitated at basic pH, whereas crystallites precipitated at pH 4.5 were hexagonal. For the same crystallite size (ca. 4.5nm), the transition temperature of the hexagonal crystallites was 315°C whereas that of the rhombus ones was only 270°C. A thermodynamic model was developed to rationalize these observations: the transition temperature results from a compromise between the crystallite size and the ratio of the lateral and basal surfaces. Consequently, the as-determined kinetic data could be a powerful tool for developing new efficient calcination processes and optimizing alumina properties.

Yves chauvin (1930-2015).

Yves Chauvin passed away at the age of 84 on January 27, 2015. We have lost a remarkable man and a prominent scientist who made momentous contributions to the field of homogeneous catalysis. He received the Nobel Prize in Chemistry in 2005 jointly with Robert H. Grubbs and Richard R. Schrock for his discoveries relating to the mechanism of olefin metathesis, a reaction that is now applied in numerous fields, as well as in industry. His fundamental scientific understanding of processes and mechanisms, and his visionary insights inspired everyone around him. Chauvin was born to French parents in Menin (Belgium), near the French border. He graduated from the École Supérieure de Chimie Industrielle de Lyon (now the École Supérieure de Chimie Physique Électronique de Lyon), in 1957. Various circumstances prevented him from pursuing a doctoral degree, which he always regretted. He started his industrial career in process development at Progil Lyon in 1958, but he left the company two years later, eager to explore new fields and ideas. He subsequently joined the Institut Français du Pétrole, now IFP Energies nouvelles, in 1960, and remained loyal to it until his retirement in 1995. He was fascinated and inspired by a number of breakthroughs at that time, for example the work by Karl Ziegler and Giulio Natta on olefin polymerization, Günther Wilke and Borislav Bogdanović on nickel-catalyzed olefin dimerization, and Geoffrey Wilkinson on rhodium-catalyzed hydrogenation. Chauvin decided to focus his early research on coordination/organometallic chemistry and homogeneous catalysis with transition-metal complexes. This discipline was embryonic in France and not yet used in the oil industry, which relied essentially on heterogeneous catalysts. Chauvin soon became France’s foremost expert in homogeneous catalysis. Chauvin looked back at 1964 as a decisive year. Three discoveries, namely the heterogeneously catalyzed disproportionation of olefins reported by Robert L. Banks from Phillips Petroleum, the homogeneous polymerization of cyclopentene published by Natta, and the new metal–carbon bond, in the carbenes, described by Ernst Otto Fischer, which seemingly had nothing in common, led to Chauvin’s major breakthrough on metathesis. The mechanism rationalized by Chauvin was later acclaimed by the entire scientific community. Apart from his work on metathesis, Chauvin investigated a large number of catalytic reactions such as polymerization and oligomerization reactions, carbonylation, hydrogenation, isomerization, and CC coupling. He took a particular interest in asymmetric amino acid synthesis. Chauvin strongly believed that fundamental research was vital to applied research and vice versa. He was able to contribute to improving industrial processes while using them for inspiration. Industrial applications were indeed his prime focus, and his research laboratory work resulted in the development of two key industrial processes in the field of homogenous transition-metal-catalyzed olefin oligomerization for refining or for petrochemistry. Chauvin was an unusually creative and successful researcher. He had no doubt that teamwork throughout the whole chain was the key to success. His research findings are the basis for more than 100 industrial processes that have been licensed worldwide. Driven by curiosity, passionate for science, always an avid reader of the literature, Chauvin had the ability to bridge the gap between fields that ignored each other. In the early 1990s, his last discovery involved applying ionic liquids, which were used as electrolytes to extend the “electrochemical windows” of batteries, as solvents for catalysis. His findings paved the way for applications in various areas and sparked keen interest from academia and industry. This was the perfect illustration of how pure science can be applied to benefit both the economy and the environment. In addition to his Nobel Prize, Chauvin, who was a member of the French Académie des Sciences, received several other distinctions including the Carl Engler medal of the Deutsche Wissenschaftliche Gesellschaft für Erdöl, Erdgas und Kohle (DGKM) in 1994. He was appointed “Grand Officier” of the Ordre National du Mérite (French National Order of Merit) in 2005 and was elevated to the highest class of “Grand-Croix” on January 21, 2015. Chauvin was also unpretentious, approachable, and keen to provide sensitive, individual guidance. He was fond of younger people, PhD students, and postdocs, and advised and encouraged them to develop their own ideas. Chauvin continued to work in research until the end of his life. He will be remembered for his impressive expertise, relentless inspiration, inquisitive mind, and passion for fundamental and applied science, as well as his loyalty and modesty. We will treasure the memories of the times we were fortunate to share with him.

Isomerization and Alkylation of Biomass-Derived Compounds in Aqueous Media over Hydrophobic Solid Acid Catalysts: A Mini Review

Isomerization and alkylation of biomass-derived compounds are key industrial processes for mitigating over dependence on fossil fuels and petrochemicals. Although designing the reactions in aqueous media is environmentally sustainable, cost-effective, and efficient, the most reliable catalysts are still being sought. We have therefore reviewed and analyzed classified literature on the prospects of hydrophobic zeolites, acidic oxides, and heteropoly acid catalysts. Emphasis was given to catalyst design, key active sites, modification, catalytic activity in related reactions, and stability properties.

Alternative Methodologies for Halogenation of Organic Compounds

It is difficult to imagine organic chemistry without organo-halogen compounds and the molecular halogens needed for their preparation. In fact, It is implied that halogenation of organic compounds is a key industrial process; for example, the halogenated products are used in the synthesis of many pesticides and pharmaceuticals. Conventional halogenation methods typically use pollutant, toxic and corrosive elemental halogens (X2), which also generate hydrohalic acid as byproduct and effectively reduce the atom efficiency. Hence, to avoid their use, various modified reagents (N-halo reagents such as trichloisocyanuric acid, haloglycolurils, N-halosuccinimid and …), methods such as oxidative halogenation in the presence of alkali halogen salts, biohalogenations, solid phase and ionic liquid have been developed. In this review article, we will focus on strategies that are much greener and more sustainable than those using elemental halogens.

Decoupling hydrogen and oxygen evolution during electrolytic water splitting using an electron-coupled-proton buffer

Hydrogen is essential to several key industrial processes and could play a major role as an energy carrier in a future 'hydrogen economy'. Although the majority of the world's hydrogen supply currently comes from the reformation of fossil fuels, its generation from water using renewables-generated power could provide a hydrogen source without increasing atmospheric CO₂ levels. Conventional water electrolysis produces H₂ and O₂ simultaneously, such that these gases must be generated in separate spaces to prevent their mixing. Herein, using the polyoxometalate H₃PMo₁₂O₄₀, we introduce the concept of the electron-coupled-proton buffer (ECPB), whereby O₂ and H₂ can be produced at separate times during water electrolysis. This could have advantages in preventing gas mixing in the headspaces of high-pressure electrolysis cells, with implications for safety and electrolyser degradation. Furthermore, we demonstrate that temporally separated O₂ and H₂ production allows greater flexibility regarding the membranes and electrodes that can be used in water-splitting cells.

Modeling the Case Hardening of Automotive Components

A generalized framework has been developed within ABAQUS to model the surface hardening heat treatment processes for automotive steel components. The macro-scale heat transfer and stress calculations during the heating and quenching are coupled with the microstructural phase calculations, defined through a user routine, to estimate key process parameters such as case depth and surface hardness. This model has been applied to predict these parameters in two key industrial processes, i.e., case hardening of crankshafts and case carburization of gears. The results of the case depth and hardness calculations have been validated with the literature and in-house plant data. The effect of varying quench conditions on the overall stress distribution changes within the component has been outlined.