Benzene Recovery Research Articles

AspenPlus-based techno-economic analysis of solar-assisted sorption-enhanced gasification for hydrogen and chemicals recovery from polyethylene terephthalate waste

Although the recycling of polyethylene terephthalate (PET) bottles is well-operating in several countries, less than 10% of PET plastic waste was recycled in a closed loop globally, and the rest was discarded as leakage. A process to recover hydrogen and valuable chemicals through solar-assisted PET sorption-enhanced gasification was analyzed. PET steam gasification with CaO and solar-assisted calcium looping processes were already experimentally studied in our previous work to obtain optimized processing conditions. In this paper, the integrated process with product purification, steam power plant, and LiBr-H2O absorption chiller was simulated with Aspen Plus based on previous experimental results to investigate the techno-economic performance. Material flows, energy balance, exergy destruction, and economics were analyzed. Day and night mode operations at different seasons were evaluated based on energy balance and the weather conditions of Naples, Italy. The energy and exergy efficiencies of day and night modes varied between 62%–72%. The annual production yields of hydrogen and benzene were 684 t and 6286 t, respectively. Due to the high production of benzene, its higher price (>1092 €/t) would make the project feasible with a larger than 12% internal rate of return value and competitive break-even hydrogen price (less than 4 €/kg). The results show that this integrated process could be technically and economically feasible. It has the potential to be implemented for hydrogen and benzene recovery from PET plastic waste with sustainable solar heat source and zero fossil CO2 emissions.

Recovery Design of Benzene and Chlorobenzene from Chlorobenzene Wastewater

Chlorobenzenes (CB) are important organic chemical and industrial product, which plays a more and more important role in chemistry and production. In this paper, the process design, process simulation and optimization of chlorobenzene wastewater produced in chlorobenzene production are carried out. The recovery of benzene and chlorobenzene in chlorobenzene wastewater can improve the economic benefit to a certain extent, which provides a theoretical basis and practical significance for the actual production operation. Based on the chlorobenzene wastewater of a chemical plant, this paper introduces a variety of processes and simple process comparisons. Finally, the stripping method is used to recycle benzene and chlorobenzene. Aspen Plus software is used to simulate and optimize the process, and the best process parameters are selected. In this paper, the process was simulated, and the sensitivity of the distillation column of the benzene and chlorobenzene separation unit was analyzed. Several operating parameters were compared and optimized to achieve the best separation effect. For the Case Study, the optimal number of trays for the rectifying tower is determined to be 20, the optimal feed position is the twelfth tray, the optimal reflux ratio is 0.70, and the optimal distillation ratio is 0.75.

Binary mixtures of choline chloride-based deep eutectic solvents as green extractants for the extraction of benzene from n-hexane

A suitable green solvent for extraction of aromatics from aliphatics must possess good solvation and physicochemical properties, a rare occurrence in a single deep eutectic solvent (DES). Mixture of DESs could enable synergy and provide a good candidate extractant. In this study, DESs of glyceline, ethaline, and reline were synthesized and their binary mixtures (glyceline/ethaline, reline/ethaline, and glyceline/reline) produced by blending in various volume proportions. Twelve of such mixed solvents were prepared and their extraction efficiency for separating benzene from n-hexane investigated in a batch equilibrium process. Liquid–liquid equilibria (LLE) data for the pseudo-ternary systems of n-hexane + benzene + mixed DESs were measured at 303 K and 101.3 kPa. The distribution coefficient (D) and selectivity (S) of each pseudo-ternary system were determined to elicit extraction efficiency. The physicochemical properties of the mixed DESs were also measured. The results show that generally the distribution coefficients, selectivities, and physicochemical properties of the mixed DESs lie between the corresponding values for the constituent DES. The best performance was given by the mixed solvent of glyceline and ethaline in the 80:20 volume ratio, respectively, with D = 0.75 and S = 422.485. This assertion was further corroborated by higher percent recovery of benzene obtained from the said mixed DES (57.88%) relative to other mixed DESs (≤ 49.11%) examined in this study. Furthermore, its separation efficiency is superior to sulfolane but lower than glyceline, though there was a 9.4% reduction in its viscosity relative to glyceline.

Improved design of separation system for the recovery of benzene and isopropanol from wastewater

In order to recover valuable benzene and isopropanol from wastewater, development of energy-efficient design flowsheet of this separation system is a relevant design problem in industry and worthy of investigation. The available separation methods in open literature were to either use a triple-column pressure swing distillation or by combining heterogeneous azeotropic distillation and pressure-swing distillation. Although the above two separation methods having the favorable feature of not introducing any foreign component into the system, the economics and energy consumption of the above separation design flowsheets can still be significantly improved. The purpose of this paper is to develop an improved design flowsheet for this separation task, not ever seen in open literature, making use of natural liquid–liquid splitting in a decanter and arranging the distillation sequence so that one of the preceding column to be designed as a stripper to preserve latent heat of this column’s top vapor stream. Further energy-saving schemes of this separation system were also thoroughly investigated. It is found that the economics of our proposed heat-integrated separation system can significantly cut 75.1% and 66.2% in total operating cost and total annual cost, respectively, as compared to that of the best separation system recently proposed in open literature.

Efficient recovery of benzene and n-propanol from wastewater via vapor recompression assisted extractive distillation based on techno-economic and environmental analysis

N-propanol and benzene are important chemical organic compounds, which widely exist in wastewater of chemical industry, medicine and other fields. Because they form azeotrope with water, extractive distillation was used to separate them. In order to increase the efficiency of energy utilization, vapor recompression technology was added on the basis of extractive distillation. On the basis of vapor recompression assisted extractive distillation, energy integration was carried out according to pinch technology, and the optimal energy utilization method was found. The exergy loss and gas emission of each process were studied and analyzed. The results show that the vapor recompression assisted distillation process with feed preheating can reduce the heat duty and gas emissions, and improve exergy efficiency and economic performance. Therefore, the vapor recompression assisted distillation process with feed preheating can effectively treat the wastewater containing benzene / n-propanol. It has the advantages of low cost, energy saving and environmental protection, which is of great significance to the development of environmental protection industry.

Production and evaluation of properties of waste-based carbon adsorbent

This paper focuses on the study of the production method, evaluation of quality indicators and application of adsorbents based on wood and common polymer wastes. The co-pyrolysis technique of polyethylene, polypropylene, polyethylene terephthalate and other polymers with sawdust at the weight ratio of 1:1 and 1:2 and temperature 370−500 °C is used for the production of adsorbents. Influence of polymer and wood type on the product quality is discussed. For the composition of birch wood and polypropylene, linear models for the yield estimation and indicators of the porous structure of adsorbents, based on the experiment planning method, are proposed, which allow us to forecast their quality under the joint influence of their production factors. The adsorbent at 500 °C was also characterized by optical and electron microscopy, X-ray fluorimetry, infrared spectrometry and low-temperature nitrogen adsorption method: its surface area (Brunauer–Emmett–Teller) is 435 m2/g, surface area of micropores (t-plot) is 316 m2/g; the average pore diameter is 1.93 nm; the total pore volume is 0.20 cm3/g. The sample at 370 °C has maximal volume of pores sorbing 0.662 cm3/g of benzene and 0.703 cm3/g of tetrachlormethane and expressed hydrophobic properties; these values are superior to those of birch activated carbon twice. Its use for the vapor recovery of benzene from the airflow was evaluated, which showed its high activity (322 mg/g) and superiority over commercial activated carbon. An approximate ecological and economic evaluation of this adsorbent production has been carried out, demonstrating its profitability and environmental effectiveness.

УЛАВЛИВАНИЕ ПАРОВ БЕНЗОЛА В ПРОЦЕССЕ ПРИГОТОВЛЕНИЯ КАТАЛИЗАТОРНОГО КОМПЛЕКСА АЛКИЛИРОВАНИЯ БЕНЗОЛА

The vapor recovery of benzene from off-gas of the catalyst preparation unit by
 absorption with polyalkylbenzenes is considered. The scheme of the process is developed, the design
 is offered and the principal absorber’s dimension for the vapor recovery of benzene are determined.

Control of a pressure-swing distillation process for benzene/isopropanol/water separation with and without heat integration

Controlling the behavior of processes for the recovery of benzene and isopropanol from industrial wastewater is an important topic. In this work, dynamic control structures are investigated for the separation of azeotropic water, benzene, and isopropanol mixtures using triple column pressure-swing distillation (without heat integration, with partial heat integration, and with full heat integration). Composition and flow disturbances are utilized to examine the performance of the control structure, and four improved control structures are developed and show good control effects. The ratio of reboiler duty to mole feed flow rate control structure showed good control behavior in face of the disturbances for the ternary pressure swing distillation processes. The integral of squared error (ISE) values of the control structure was combined with the dynamic response curves to compare the performance of the control structures. The ISE value of the improved control structure with full heat integration was smaller than that of the improved control structure without heat integration and the improved control structure with partial heat integration. The total annual cost (TAC) of the full heat integration process was also lower than the values for the other three processes. Based on its control performance and TAC, the improved control structure with full heat integration was concluded to be the best of the control structures. This work can serve as a reference for industrial development.

A holistic life cycle evaluation of coking production covering coke oven gas purification process based on the subdivision method

The accuracy of life cycle assessment (LCA) results largely depends on data quality. Coking production is a multi-functional system that generally consists of coke-making process and coke oven gas (COG) purification process. Previous LCA studies mainly investigated the overall impacts of coking production without identifying the specific contribution of sub-processes due to lack of enough data. The present study aims to provide a holistic “cradle to gate” LCA on coking production based on the subdivision method. The COG purification process was specially addressed from four sub-processes, including blowing cooler system, sulfur recovery, ammonia recovery and raw benzene recovery. LCA results referred to 1 ton of coke was analyzed by the subdivision method and compared with physical and economic allocation methods. LCA evaluation was performed by five mid-point categories from CML 2001 method combined with three human toxicity categories from IMPACT 2002 + method.The results indicated that COG purification process showed comparable or more significant contribution as coke-making process to the overall life cycle air emissions of coking production. In COG purification process, ammonia recovery and blowing cooler system units were the dominating contributors, mainly attributed to steam usage and electricity consumption in each unit. Compared to physical and economic allocation methods, using subdivision method is more reasonable and accuracy for all the products in coking production. The study helps to better identify the specific environmental hotspots and improvement opportunities for coking industry from a more holistic perspective.

SIMULTANEOUS TRACE LEVEL DETERMINATION OF BENZENE AND 1, 2-DICHLOROETHANE BY GC-HS/GC-MS IN SEVERAL PHARMACEUTICAL DRUG SUBSTANCES

Objective: We herein report the simultaneous trace level determination of benzene and 1,2-dichloroethane in several active pharmaceutical substances by GC-HS (gas chromatograph-head space) using a DB-624 column.Methods: This GC-HS method was developed based on an oven-programmed approach using nitrogen gas as the mobile phase. Our method is also compatible with the GC-MS (gas chromatography-mass spectrometry) technique using helium as the mobile phase instead of nitrogen. The successful separation of benzene and 1,2-dichloroethane was established by confirmation of their corresponding specific molecular masses.Results: The retention time of benzene and 1,2-dichloroethane were found to be 34.8 min and 35.6 min, respectively. The linearity was found in the range of concentration of 0.63-4.22 ppm and 1.49-9.96 ppm for benzene and 1,2-dichloroethane. The detection limit and quantification limit for benzene were 0.2 and 0.6 ppm, while those of 1,2-dichloroethane were 0.6 ppm and 1.5 ppm. These values were calculated using our developed method with respect to the test concentration of 500 mg/ml. The recovery of benzene and 1,2-dichloroethane were found to be 89–110% and 91–105%, respectively for the various pharmaceutical drug substances. The specificity of the method was studied using 20 solvents which include benzene and 1,2-dichloroethane.Conclusion: We expect that our method will be applicable for the simultaneous trace level determination of benzene and 1,2-dichloroethane during the control of manufacturing processes, and for use in rapid analysis for quality control in the pharmaceutical industry. Finally, this method was validated according to the International Conference on Harmonization (ICH) Validation Guidelines Q2 (R1).

Corrosive Activity of Coal-Tar Wash Oils and Life of Equipment in Benzene Recovery

The corrosive activity of coal-tar wash oils is investigated. An electrochemical method is proposed for assessing the corrosive activity of the oil with respect to carbon steel. The main sources of corrosive impurities in the absorbers are identified. The contamination of the oil is assessed on the basis of its breakdown voltage. The results are in excellent agreement with analytical monitoring of the wash oils. Gravimetric data for the corrosive activity of the fluids in the existing system show that alloyed molybdenum steels are the most durable structural materials in the distillation department. In systems with a closed final-cooling cycle, the corrosive activity of the coal-tar oils may be reduced by scrubbing with water. Quantitative selection criteria are established for the water used.

Managing Exposure to Benzene and Total Petroleum Hydrocarbons at Two Oil Refineries 1977-2014.

Air concentrations of and inhalation exposure to total petroleum hydrocarbons (TPH) and benzene was monitored separately at two oil refineries from 1977 to 2014. Prevention policies and control measures that may explain changes were surveyed. The aim was to evaluate how the application of of Occupational Health and Safety Assessment Series OHSAS 18001.04 principles as well as Environmental protection Agency EPA and European Oil Company Organisation for Environment, Health and Safety CONCAWE practices have influenced air concentrations. Benzene air concentrations declined in 11 of 17 units, six of which were associated with declining exposures. Benzene air concentrations declined across all units on average by 46%. This amounts to an average yearly decline of 1.7%. TPH air concentrations declined in 10 of 17 units, seven of which were associated with declining exposures. The average decline in TPH air concentrations was 49%, corresponding to 1.3% per year. As a result, average working day exposure in 10 of 17 units have declined significantly and today, benzene and TPH exposure in most units are well below 10% of the current Occupational Exposure Limit (OEL8h:s). A decline in air concentrations have coincided with consistent implementation of control measures. Such measures include on-line monitoring of leaks; benzene recovery; floating container roofs; improved valves and seals; hermetic pumps; recovery of loading gases and instalment of torches in terminals; cutback in coke combustion; a new production line spanning directly from the dock to aromatics production; and recovery of loading gases in the doc. Other tools in exposure management include personal leak monitors, on-line measurements, monitoring campaigns, risk assessment, and availability and user training of protective equipment. However, improvements are still needed. Hydrocarbon or benzene air concentrations have not declined in 8 of 17 units, in some of which concentrations exceed 10% of the relevant OEL8h value. In addition, for benzene even 10% of the current OEL, 0.1 ppm, might still possess a risk. With this in mind, methods to estimate exposure at the refineries need to be improved to enable measuring benzene concentrations <0.1 ppm. Shut downs of the refinery have been associated with peaks in exposure concentrations. Consequently, effort should be placed on safe working methods pertaining to shutdowns. Also, the connection and detachment of hoses continues to be problematic from the point of view of controlling exposure.

Energy‐Saving Hydrocarbon Distillation with Coupled Heat and Material Flows

AbstractHigh energy consumption during distillation is a problem in petrochemical and refining industry. Therefore, the distillation of hydrocarbons was investigated with the aim to reduce the energy consumption by applying columns with fully or partially thermally coupled heat and material flows. The elements of downstream processes were considered, such as the separation of catalytic cracking gas and the recovery of benzene from petroleum and coking coal products by extractive distillation with N‐methylpyrrolidone. It was found that the thermally coupled columns applied for the separation reduced the energy consumption for catalytic cracking gas separation by up to 13.1 % and for benzene recovery by up to 28.7 %.

EFFECT OF PALM OIL FIBER-TiO2 RATIO IN THE COMPOSITE ON THE REDUCTION OF BTX AND FORMALDEHYDE IN THE AIR

The effect of palm oil fiber-TiO2 ratio in the composite on the reduction of benzene, toluene, xylene and formaldehyde in the air is studied. The ratio was set at 1:0, 1:9 and 5:5. The combination of adsorption process by palm oil fiber and photooxidation of volatile organic compounds by titanium dioxide was revealed. The composite were prepared by using mechanical milling technique. The performance of the composite was characterized in terms of percentage of recovery of benzene, toluene and xylene (BTX) using GC/FID and formaldehyde concentration reduction using formaldehyde meter. The results of recovery of the BTX by palm oil fiber/titanium dioxide composite were more than 90%. The palm oil fiber/titanium dioxide composite has successfully reduced the concentration of formaldehyde by up to 66.7%. Therefore, the palm oil mesocarp fiber/titanium dioxide composite produced is able to reduce the concentration of volatile organic compounds.

Extracción de benceno en efluentes de la industria petroquímica

The simulation calculations are presented in the liquid-liquid extraction operation of typical petrochemical industry streams, mainly composed of heptane and benzene. The solvent chosen based on the chemical properties of the system formed is DMF (dimethylformamide), thus studying its liquid-liquid equilibrium topology in order to evaluate the viability of the extraction operation. Simulation calculations are shown using Tsuboka y Katayama (1976) ISR strategies to evaluate the percentage of benzene recovery, which will subsequently be the basis for the implementation of this operation in the use of High environmental impact, thus avoiding its disposition in nature. This project is considered as a proposal in order to reduce the environmental consequences caused by the release of apolar substances in nature, taking them to a level where they can be used as raw materials for other industrial processes, solvents Or additives, thus generating added value by using substances that with an unproductive vision would be discarded. The recovery rate was 96.2%, high enough to be considered as a proposal for industrial application.

Reprint of: Simulation based ionic liquid screening for benzene–cyclohexane extractive separation

In order to screen ionic liquids (IL) as suitable solvents for the separation of benzene and cyclohexane, the extraction efficiency of ILs (12 cations and 22 anions) was estimated based on COSMO-RS predictions of infinite dilution activity coefficients of benzene and cyclohexane in different ILs..[C4mim][AlCl4] was found to be the most promising solvent. To provide deep insight on how the IL structure influences the extraction efficiency, molecular interactions between IL ions and benzene were determined from DFT calculations. Moreover, liquid–liquid equilibrium data of the ternary system benzene–cyclohexane—[C4mim][AlCl4] were experimentally determined and used to fit parameters of the NRTL activity coefficient model. Based on the NRTL model the continuous extraction process was simulated and compared with a reference process using sulfolane as solvent. For the extraction process using [C4mim][AlCl4], high cyclohexane product purity (99.65wt%) and high benzene recovery efficiency (98.03%) can be reached with at much lower energy consumption and higher product yield compared to conventional extraction solvents. In conclusion, the ionic liquid [C4mim][AlCl4] is a promising solvent for the extractive separation of benzene and cyclohexane.

Catalytic Degradation of Poly(ethylene terephthalate) for Benzene-rich Oil Recovery Using Metal Hydroxides

Poly(ethylene terephthalate) (PET) was pyrolyzed in the presence of several metal hydroxides for the high-yielding recovery of benzene in one benzene-rich fraction. The highest benzene yield of 80....

Simulation based ionic liquid screening for benzene–cyclohexane extractive separation

In order to screen ionic liquids (IL) as suitable solvents for the separation of benzene and cyclohexane, the extraction efficiency of ILs (12 cations and 22 anions) was estimated based on COSMO-RS predictions of infinite dilution activity coefficients of benzene and cyclohexane in different ILs..[C4mim][AlCl4] was found to be the most promising solvent. To provide deep insight on how the IL structure influences the extraction efficiency, molecular interactions between IL ions and benzene were determined from DFT calculations. Moreover, liquid–liquid equilibrium data of the ternary system benzene–cyclohexane—[C4mim][AlCl4] were experimentally determined and used to fit parameters of the NRTL activity coefficient model. Based on the NRTL model the continuous extraction process was simulated and compared with a reference process using sulfolane as solvent. For the extraction process using [C4mim][AlCl4], high cyclohexane product purity (99.65wt%) and high benzene recovery efficiency (98.03%) can be reached with at much lower energy consumption and higher product yield compared to conventional extraction solvents. In conclusion, the ionic liquid [C4mim][AlCl4] is a promising solvent for the extractive separation of benzene and cyclohexane.

Simultaneous Recovery of Benzene-Rich Oil and Metals by Steam Pyrolysis of Metal-Poly(ethylene terephthalate) Composite Waste

The possibility of simultaneous recovery of benzene and metals from the hydrolysis of poly(ethylene terephthalate) (PET)-based materials such as X-ray films, magnetic tape, and prepaid cards under a steam atmosphere at a temperature of 450 °C was evaluated. The hydrolysis resulted in metal-containing carbonaceous residue and volatile terephthalic acid (TPA). The effects of metals and additives on the recovery process were also investigated. All metals were quantitatively recovered, and silver, maghemite (γ-Fe2O3), and anatase (TiO2) were recovered without any changes in their crystal structures or compositions. In a second step, TPA was decarboxylized in the presence of calcium oxide (CaO) at 700 °C, producing benzene with an average yield of 34% and purity of 76%. Maghemite (γ-Fe2O3) incorporated in magnetic tape and prepaid cards could decarboxylate TPA. Aluminum present in the prepaid cards produced hydrogen by the reaction with steam. However, the presence of metals had no adverse influence on the recovery of benzene-rich oil in the presence of CaO. Therefore, this method can be applied to PET-based materials containing inorganic substances, which cannot be recycled effectively otherwise.

Benzene recovery at PAO AKKhZ

The measures adopted in the benzene department of byproduct-capture shop 1 at PAO Avdeevskii Koksokhimicheskii Zavod (AKKhZ) are discussed. During the reconstruction of coke production at the plant, valuable operational experience has been gained with a compact cooling system for the coke-oven-gas and a modernized benzene scrubber. A simplified system is proposed for the distillation column.