Styrene Production Research Articles

Minimizing Process Water and Energy Consumption in Styrene Production by Ethylbenzene Dehydrogenation

Styrene is a crucial unsaturated aromatic monomer with a wide range of industrial applications. Styrene production faces several problems where the water supply and energy usage are keep increasing. Process modifications were implemented to minimize process water and to optimize the energy consumption. The modification uses Aspen HYSYS simulation by replacing coolers and heaters with heat exchanger and implementing water recycling system. Aspen HYSYS simulations show these changes reduce water usage by 89.8% and significantly decrease energy consumption up to 54.69%. This modification shows the water and energy usage have been significantly reduced than the basic process. Copyright © 2024 by Authors, Published by Universitas Diponegoro and BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Dental status as an indicator of the intensity of exposure to chemical pollution of the air in the working area

Introduction. Lack of knowledge of the oral status in chemical production workers determines the relevance of this study. In most studies, we did not find sufficiently comprehensive information about working conditions. Aims. To assess the risks of developing somatic and dental pathologies among chemical production operators depending on the intensity and duration of exposure to chemical factors in order to reduce the occupational cause of health deterioration. Materials and methods. A comprehensive clinical and hygienic examination was conducted in eight hundred seventy eight isoprene, divinyl, styrene, ethylene oxide production apparatchiks who were exposed to harmful substances. The working conditions are analyzed according to the production control data. The analysis of the microbial profile in periodontal pockets in 128 workers by polymerase chain reaction was performed. Results. In the studied industries, differences were noted in the levels of exposure of the chemical factor to the body: in the production of divinyl and isoprene, working conditions corresponded to hazard class 3.1, styrene to class 3.2, ethylene oxide to class 3.3. Styrene production workers had a high degree of industrial conditionality of chronic cholecystitis (RR=2.16; EF=53.6%), biliary dyskinesia paths (RR=2.53; EF=60.5%). Ethylene oxide production apparatchiks showed a high degree of industrial conditionality of subatrophic nasopharyngitis (RR=2.60; EF=61.6%), chronic catarrhal laryngitis (RR=2.83; EE=64.7%), and severe chronic periodontitis (RR=2.36; EF=57.7%). The high prevalence of periodontopathogens P. Gingivalis and A. Actinomycetemcomitans has been shown. Limitation. The lack of immunological and cytogenetic analysis data necessary for preclinical diagnosis of pathological changes in the oral cavity. Conclusion. Significant differences in the level of exposure of the chemical factor to the health in workers have been revealed. A high degree of industrial conditionality of a number of somatic diseases in workers of styrene and ethylene oxide industries has been determined. The greatest deviations in the state of oral health were observed in ethylene oxide production workers with more than 20 years of work experience. Differences in the species composition of the microbiome of periodontal pockets in ethylene oxide apparatchiks, depending on work experience, were detected.

Prediction of the thermal degradation–induced colour change of acrylonitrile butadiene styrene products as a function of temperature and titanium dioxide content

In this study, we examined the thermal degradation–induced colour change of acrylonitrile butadiene styrene (ABS)–based titanium dioxide (TiO2)–doped products as a function of TiO2 content and temperature. Based on the time–temperature superposition (tTS) principle and the CIELAB colour space, we proposed a methodology for developing a robust model to estimate the long-term colour change of polymers doped with TiO2 at elevated temperatures. We used 800 h of measurement data to develop the model and validated the colour change predictions of the model in 1600 h. The average colour difference between the measured and modelled results at the application temperature range (below 80 °C) was <1.5, smaller than the just noticeable difference (JND) in the CIELAB colour space. We found that above a certain TiO2 content (approximately 3 wt%), the colour retention of the ABS/TiO2 specimens can no longer be improved by increasing their TiO2 content. To show the applicability of the model, we present two simple case studies predicting the colour and appearance of a polymer product under constant and variable heat loads. The proposed methodology provides an excellent tool for design, as it can be used to determine the optimum amount of TiO2. Moreover, it accelerates and simplifies the design process.

Providing a new route for chemical recycling of plastics by aspen plus simulation, energy, and its carbon dioxide emissions analysis

In this research, a new complex is proposed for chemical recycling of plastic. After determining the plastic waste entering this process, the sections in which chemical reactions occur have been simulated through aspen plus, such as: gasification of plastic waste and purifying, methanol production, methanol decomposition to various chemicals such as ethylene, propylene, and methane, separation processes for these products, methane decomposition to benzene and the separation of the products of this part, single-step production of styrene from benzene and ethylene, and the polymerization processes. Furthermore, the impacts of this complex on issues such as plastic recycling, energy consumption, and carbon dioxide emissions are studied and compared to conventional methods of plastic production. Results indicate that plastic waste recycling will be >98 % in the proposed model. Energy consumption is decreased by 29 %, carbon dioxide in this part is decreased by 53 % by using renewable energy for its power consumption. These results show the sustainability, and circularity of the proposed model.

Intergrowth MFI Zeolite with Inverse Al Zoning and Predominant Sinusoidal Channels for Highly Selective Production of Styrene.

ZSM-5 zeolites with accessible micropore architecture and tunable acid-base sites are important shape-selective catalysts. However, the presence of exposed straight channels and the external acid-base sites of conventional ZSM-5 has a negative impact on shape selectivity. Herein, we report on the direct synthesis of an intergrowth ZSM-5 zeolite mimicking the mortise-tenon joints. It can be revealed by various methods that the mortise-tenon ZSM-5 shows an inverse Al gradient from the surface to the core of the zeolite. More importantly, the sinusoidal channels predominantly opened to their external surfaces are constructed. The shape-selective capability of the ZSM-5 zeolite has been fully exploited due to the intrinsic inert external surface and unique sinusoidal channel features, thereby resulting in high styrene selectivity (>90%) and good catalytic stability (>100 h) in the toluene side-chain alkylation reaction. In addition, in situ DRIFTS confirms that this intergrowth ZSM-5 contributes to the formation of more active intermediates of HCOO* and H3CO*, which is another reason responsible for the superior performance.

Autoassociative neural network for missing data imputation: A case study via the styrene production process

AbstractA neural network‐based model is proposed to estimate missing values of incomplete datasets to augment their size. An autoassociative neural network (AANN), for which the output vector is identical to the input vector, was built for a styrene production process dataset. The proposed model was used to investigate the ability of an AANN to estimate one to three missing variables, evaluating the impact of the size of the datasets used and the level of correlation of the missing values with other process variables. Results show that the proposed AANN model can predict the process data even when the number of records used is relatively small. Moreover, the AANN method is suitable for estimating missing variables with an accuracy that depends on the correlation coefficient of the missing values with other process variables, keeping acceptable estimation for weakly‐correlated variables. Moreover, the model was tested on noisy data, and it is shown that the model trained on noisy data can also predict missing values in an acceptable estimation range.

Implementing multiblock techniques in a full-scale plant scenario: On-line prediction of quality parameters in a continuous process for different acrylonitrile butadiene styrene (ABS) products

BackgroundThe study explores the challenges of handling multiblock data of different natures (process and NIR sensors) for on-line quality prediction in a full-scale plant scenario, namely a plant operating in continuous on an industrial scale and producing different grade Acrylonitrile Butadiene Styrene (ABS) products. This environment is an ideal scenario to evaluate the use of multiblock data analysis methods, which can enhance data interpretation, visualization, and predictive performances. In particular, a novel multiblock extension of Locally Weighted PLS has been proposed by the authors, namely Locally Weighted Multiblock Partial Least Squares (LW-MB-PLS). Response-Oriented Sequential Alternation (ROSA) has also been employed to evaluate the diverse block relevance for the prediction of two quality parameters associated with the polymer. Data are split in blocks both according to sensor type and different plant sections, and different models have been built by incremental addition of data blocks to evaluate if early estimation of product quality is feasible. ResultsROSA method showed promising predictive performance for both quality parameters, highlighting the most influential plant sections through the selection of data blocks. The results suggested that both early and late-stage sensors play crucial roles in predicting product quality. A reasonable estimation of quality parameters before production completion has been achieved. On the other hand, the proposed LW-MB-PLS, while comparable in predictive performances, allowed reducing systematic prediction errors for specific products. SignificanceThis study contributes valuable insights for continuous production processes, aiding plant operators and paving the way for advancements in online quality prediction and control. Furthermore, it is implemented as a locally weighted extension of MB-PLS.

Orthogonal experimental study of ultrasound-assisted fused deposition molding

To improve the quality of fused deposition molding (FDM), we introduced ultrasonic vibration into the molding process to enhance the strength of the tensile samples. We used the response surface method to optimize the FDM molding process. We carried out orthogonal experiments to investigate the effects of ultrasonic power and process parameters (extrusion temperature, hotbed temperature, and delamination thickness) on the mechanical properties of fused deposition acrylonitrile butadiene styrene products. We obtained the quadratic regression equations and response surfaces of the data through analysis of variance and significance analysis by software. Last, we received the optimum combination of process parameters for tensile strength as extrusion temperature 233.85 °C, hotbed temperature 93.38 °C, delamination thickness 0.1 mm, and ultrasonic power 43.09 W.

Rapidly solidified Al-Cu-Co quasicrystalline alloy: microstructure and catalytic properties

This study presents the characterisation and evaluation of the catalytic potential of an alloy with a composition referring to the quasicrystal from the Al-Cu-Co system. The material was synthesised through a melt-spinning process, providing rapid solidification conditions and a favourable material form of thin ribbons. Microstructural and chemical analyses were performed using scanning electron microscopy, X-ray diffraction and transmission electron microscopy methods. The obtained results confirmed the presence of a major phase which was a decagonal quasicrystal in the form of globular grains and additional crystalline phases occurring along the grain boundaries. The catalytic potential of the materials was explored using phenylacetylene hydrogenation. The catalyst, obtained by pulverising the ribbons, demonstrated catalytic activity with over 40% phenylacetylene conversion and selectivity exceeding 60% for styrene production under mild reaction conditions. The recovered catalyst displayed a stable phase composition, as confirmed by X-ray diffraction, and unchanged morphology, indicating the possibility of catalyst reuse for subsequent reaction cycles. The presented results provide insight into the experimental verification of the catalytic properties of the developed environmentally friendly catalysts.

Interrelations between Printing Patterns and Residual Stress in Fused Deposition Modelling for the 4D Printing of Acrylonitrile Butadiene Styrene and Wood–Plastic Composites

Four dimensional printing enables the advanced manufacturing of smart objects that can morph and adapt shape over time in response to stimuli such as heat. This study presents a single-material 4D printing workflow which explores the residual stress and anisotropy arising from the fused deposition modelling (FDM) printing process to create heat-triggered self-morphing objects. In particular, the study first investigates the effect of printing patterns on the residual stress of FDM-printed acrylonitrile butadiene styrene (ABS) products. Through finite element analysis, the raster angle of printing patterns was identified as the key parameter influencing the distribution of residual stresses. Experimental investigations further reveal that the non-uniform distribution of residual stress results in the anisotropic thermal deformation of printed materials. Thus, through the design of printing patterns, FDM-printed materials can be programmed with desired built-in residual stresses and anisotropic behaviours for initiating and controlling the transformation of 4D-printed objects. Using the proposed approach, any desktop FDM printers can be turned into 4D printers to create smart objects that can self-morph into target geometries. A series of 4D printing prototypes manufactured from conventional ABS 3D printing feedstock are tested to illustrate the use and reliability of this new workflow. Additionally, the custom-made wood–plastic composite (WPC) feedstocks are explored in this study to demonstrate the transposability of the 4D printing approach.

Investigating the Role of Cs Species in the Toluene–Methanol Side Chain Alkylation Catalyzed by CsX Catalysts

The side chain alkylation of toluene with methanol was studied on a series of CsX catalysts prepared by varying the Cs species and ion exchange conditions. The effects of various parameters, such as the exchanging temperatures and times on the adsorption/activation properties of different CsX catalysts, were investigated by combining a variety of characterization means for understanding the role of Cs species in the side chain alkylation reaction. On the basis of the various characterization results and their related literature results, it can be proposed that the Cs ions located on the ion-exchanged sites of X zeolites could effectively adsorb and activate toluene molecularly through modifying the basicity of framework oxygen, whereas the cluster of cesium oxide (Cs2O) could ensure the effective conversion of methanol into formaldehyde. Additionally, Cs ions can promote the production of monodentate formate, which enhances the selectivity of styrene. However, too much Cs2O will lead to the excessive decomposition of methanol into CO2, CO, and H2, thus inhibiting the production of styrene. In summary, the presence of suitable amounts of Cs ions and Cs2O clusters plays a significant role in the formation of the side chain products of styrene and ethylbenzene.

Catalytic fast pyrolysis over heavy metals-containing livestock manure biochar catalyst for polystyrene upcycling

The perpetual market demand for polystyrene results in the gradual accumulation of polystyrene waste, placing a serious burden on the environment. This study proposed a promising method to upcycle polystyrene for styrene-derived monomers through catalytic fast pyrolysis. The metals-incorporated biochar catalysts were synthesized from heavy metals-contaminated manure waste for catalytic fast pyrolysis of polystyrene. The experimental results showed that the bimetallic biochar-derived catalyst containing Zn and Cr (Zn-Cr/C) was more conducive to the liquid production, with an extremely high yield of 88.22 wt%. Monometallic Pb-incorporated biochar catalyst (Pb/C) and bimetallic Zn-Cu co-doped on biochar (Zn-Cu/C) were more favorable for the production of pure styrene, with the mass yield of 61.26 wt% and 60.39 wt%, respectively. Additionally, the study elucidated a deep understanding of the reaction mechanisms involved in the catalytic fast pyrolysis of polystyrene. Simply put, this study introduced a new concept to convert heavy metal-contaminated animal manure into metal-incorporated biochar catalysts for catalytic conversion of polystyrene waste in pure styrene-based monomers.

Оценка условий труда по химическому фактору при комбинированном воздействии вредных веществ

The variety of chemical compounds contained in complex mixtures and various chemical substances circulating in the workflow conditions potentially highly hazardous chemical impact on workers. Long-term studies indicate the need to take into account the combination of harmful substances with the summation effect when evaluating the chemical factor, which is often not conducted in practice. When assessing working conditions by chemical factors, various combinations of substances with potentially increasing impact on bodies of workers engaged in styrene production and thereby worsening the working conditions have been considered: with similar chemical structure and equal biological impact. During a shift at a workplace, the most common situation is when the excess of concentration of each of harmful substances in the air might not be registered, therefore, working conditions are assessed in such case as acceptable, which objectively does not reflect the potential risk of damage to health caused by chemical factor. It has been demonstrated that, when assessing working conditions by this factor, accounting for the combination of harmful substances of unidirectional impact and summation effect can significantly change the class of working conditions and increase the harmfulness by 1–2 levels. It has been established that with a greater amount of harmful substances contained in the air of the working area and a combined effect of exposure, the permissible limit of summation coefficient will be exceeded even at concentrations significantly lower than those established by standards. This will allow assessing working conditions by chemical factor as a class of greater harmfulness. The above-mentioned implies the need to account for the combined effect when establishing a class of working conditions in order to obtain the objective evaluation of hygienic situation at a chemical production facility.

Redox oxidative dehydrogenation of ethylbenzene over Mn–Al–O composites using active lattice oxygen at moderate temperatures

Oxidative dehydrogenation (ODH) of ethylbenzene is a promising process for styrene production. However, its application is limited by product overoxidation and purification requirements due to the co-feeding of mild oxidants. Herein, we report a facile manganese-based catalyst (K/Mn3O4-Al2O3) and achieve competitive styrene selectivity of 88 % and ethylbenzene conversion of 95 % at 450 ℃ (84 % yield vs. ∼ 60 % yield in commercial dehydrogenation process at 600 ℃) under a cyclic redox ODH scheme. The introduction of Al2O3 into MnOx restructures composite oxides and depresses bulk lattice-oxygen migration for the partial oxidation of ethylbenzene. The surface modification using potassium creates reactive sites and regulates surface properties, achieving ethylbenzene activation and high conversions. Highly active lattice oxygen in catalysts after bulk and surface modifications selectively converts ethylbenzene to styrene and water. This study provides an understanding of roles of manganese-based catalysts in styrene generation and offers a strategy to modulate lattice oxygen on catalysts.

Promotional effect and mechanism of SiO2 on Cr-Al2O3 catalysts for N2O-assisted oxidative dehydrogenation of ethylbenzene

A series of Cr-SiO2-Al2O3 (abbreviated as Cr-Si-Al) catalysts were synthesized using an evaporation induced self-assembled (EISA) method and applied to the N2O-assisted dehydrogenation of ethylbenzene (EB), offering a versatile solution for greenhouse gas recycling and a novel pathway for styrene (ST) production. Notably, the Cr-5Si-Al catalyst calcinated at 850 °C exhibited remarkable performance with a high EB conversion of 71% and a good ST selectivity of 62%, resulting in an optimal ST yield of nearly 44%. To elucidate the impact of calcination temperature and reveal the underlying promoting mechanism, numerous types of characterization particularly in-situ DRIFTS were used. Results indicated that the Cr-5Si-Al-850 catalyst possessed a distinctively ordered mesoporous structure, which improved the specific surface area and facilitated the dispersion of active species. The interaction among the multiple species in the catalyst was enhanced under the high calcination temperatures, leading to an increased ratio of Cr6+ and Oα, and thus promoting the dehydrogenation of EB. Furthermore, in situ DRIFTS revealed two favorable reaction pathways: one involving the reaction between adsorbed N2O and EB, and the other involving the reaction between adsorbed EB and N2O. These pathways led to the formation of a similar intermediate, observed at a wavenumber of 1285 cm−1. The improved adsorption of EB played a pivotal role in the excellent catalytic performance of the Cr-5Si-Al-850 catalyst.

Engineering styrene biosynthesis: designing a functional trans-cinnamic acid decarboxylase in Pseudomonas

We are interested in converting second generation feedstocks into styrene, a valuable chemical compound, using the solvent-tolerant Pseudomonas putida DOT-T1E as a chassis. Styrene biosynthesis takes place from L-phenylalanine in two steps: firstly, L-phenylalanine is converted into trans-cinnamic acid (tCA) by PAL enzymes and secondly, a decarboxylase yields styrene. This study focuses on designing and synthesizing a functional trans-cinnamic acid decarboxylase in Pseudomonas putida. To achieve this, we utilized the “wholesale” method, involving deriving two consensus sequences from multi-alignments of homologous yeast ferulate decarboxylase FDC1 sequences with > 60% and > 50% identity, respectively. These consensus sequences were used to design Pseudomonas codon-optimized genes named psc1 and psd1 and assays were conducted to test the activity in P. putida. Our results show that the PSC1 enzyme effectively decarboxylates tCA into styrene, whilst the PSD1 enzyme does not. The optimal conditions for the PSC1 enzyme, including pH and temperature were determined. The L-phenylalanine DOT-T1E derivative Pseudomonas putida CM12-5 that overproduces L-phenylalanine was used as the host for expression of pal/psc1 genes to efficiently convert L-phenylalanine into tCA, and the aromatic carboxylic acid into styrene. The highest styrene production was achieved when the pal and psc1 genes were co-expressed as an operon in P. putida CM12-5. This construction yielded styrene production exceeding 220 mg L−1. This study serves as a successful demonstration of our strategy to tailor functional enzymes for novel host organisms, thereby broadening their metabolic capabilities. This breakthrough opens the doors to the synthesis of aromatic hydrocarbons using Pseudomonas putida as a versatile biofactory.

Synthesis of Styrenes and E‐Stilbenes by Palladium‐Catalyzed Vinylation of Aryl Iodides with 1,2‐Dibromoethane

AbstractThe Pd‐catalyzed vinylation reactions of aryl iodides using 1,2‐dibromoethane is developed for the synthesis of styrenes and stilbenes. In these reactions, vinyl bromide is generated from 1,2‐dibromoethane and then undergoes reductive cross‐coupling with aryl iodides, affording styrene products. Under slightly modified reaction conditions, styrenes can continue reacting with vinyl bromide to form E‐stilbenes, which provides a one‐pot synthetic method for stilbenes. Alcohols, including iso‐propanol and methanol, are employed as the reductant in these reductive cross‐coupling reactions.

Electronic structure modulation of metallic Co via N-doped carbon shell and Cu-doping for enhanced semi-hydrogenation of phenylacetylene to styrene

Styrene, an important monomer in the production of polystyrene, is usually mixed with a small number of phenylacetylene which readily causes the poisoning of catalyst during styrene polymerization. To address this issue, we reported a nitrogen-doped carbon encapsulated CuCo bimetallic catalyst (CuxCo@NC) for styrene production from phenylacetylene semi-hydrogenation. The CuxCo@NC catalyst obtained a 100% conversion of phenylacetylene along with a high 94.6% selectivity of styrene, far higher than those of single metal Co@C and Co@NC catalysts. Detailed characterizations unveiled that the CuxCo@NC catalyst fabricated by a dual-regulation strategy showed Mott-Schottky effect, in which the electrons transferred from metallic Cu to Co and then to outer N-doped carbon shells. Moreover, the electron transfers of metallic Co could be regulated by Mott-Schottky effect with which to improve the semi-hydrogenation of phenylacetylene to styrene. This work provides an feasible pathway to effectively design the supported metal catalysts for highly selective semi-hydrogenation of alkynes to alkenes.

Exploring Alternatives to Create Digital Twins from and for Process Simulation

In this work, Digital Twins based on Neural Networks for the steady state production of styrene were generated. Thus, both the Aspen Technology AI Model Builder (alternative 1) and a homemade MS Excel VBA code connected to Aspen HYSYS and Aspen Plus (alternative 2) were used with this same aim. The raw data used for generating the Digital Twins were obtained from process simulations using Aspen HYSYS and/or Aspen Plus, which were connected through a recycle-like stream via automation for solving the entire simulation flowsheet. Aspen HYSYS was used for solving the pre-heating, reaction, and stabilization sections of the process whereas Aspen Plus ensured the computing of the separation and purification columns. Both alternatives led to an excellent prediction showing the capability of creating Digital Twins from and for process simulation.

Styrene Production in Genetically Engineered Escherichia coli in a Two-Phase Culture.

Styrene is an important industrial chemical. Although several studies have reported microbial styrene production, the amount of styrene produced in batch cultures can be increased. In this study, styrene was produced using genetically engineered Escherichia coli. First, we evaluated five types of phenylalanine ammonia lyases (PALs) from Arabidopsis thaliana (AtPAL) and Brachypodium distachyon (BdPAL) for their ability to produce trans-cinnamic acid (Cin), a styrene precursor. AtPAL2-expressing E. coli produced approximately 700 mg/L of Cin and we found that BdPALs could convert Cin into styrene. To assess styrene production, we constructed an E. coli strain that co-expressed AtPAL2 and ferulic acid decarboxylase from Saccharomyces cerevisiae. After a biphasic culture with oleyl alcohol, styrene production and yield from glucose were 3.1 g/L and 26.7% (mol/mol), respectively, which, to the best of our knowledge, are the highest values obtained in batch cultivation. Thus, this strain can be applied to the large-scale industrial production of styrene.