Recovery Of Styrene Research Articles

Total revalorization of high impact polystyrene (HIPS): enhancing styrene recovery and upcycling of the rubber phase

The styrene recovery from high impact polystyrene waste can be enhanced by pre-fractionation with ethyl acetate followed by pyrolysis of the isolated polystyrene phase and ethenolysis of the polybutadiene phase.

Recovery of styrene from waste wind turbine blades (fiberglass/polyester resin composites) using pyrolysis treatment and its kinetic behavior

Recovery of styrene from waste wind turbine blades (fiberglass/polyester resin composites) using pyrolysis treatment and its kinetic behavior

DEVELOPMENT OF TECHNOLOGICAL SOLUTIONS TO REMOVE POLYMER DEPOSITS FROM THE INTERNAL SURFACE OF STYRENE PRODUCTION PIPELINES

Styrene, methylstyrenes and other substituted vinylbenzenes are thermally unstable compounds and spontaneously polymerize already at room temperature during storage and transportation. As the temperature rises, the rate of spontaneous polymerization sharply increases. Uncontrolled polymerization that occurs during the process of styrene recovery from the products of ethylbenzene dehydrogenation at the rectification stage often leads to clogging of equipment with polymer. This phenomenon can cause significant economic damage in the event of unforeseen shutdowns or unstable operation of process equipment.The article considers a method for removing polymer deposits from the inner surface of styrene production pipelines. The data of laboratory analyzes of polymer deposits are given: the solubility of the latter in a number of organic solvents of the aromatic series was studied, the ash content was determined, the presence of a significant amount of iron oxides in the ash was shown, the presence of aluminum was qualitatively confirmed; the methods of thermogravimetric analysis and differential scanning calorimetry proved the polymeric nature of the deposits; IR spectroscopy showed the identity of the structure of deposits and polystyrene. Based on laboratory studies, the composition of the washing liquid was selected, which includes toluene and a surfactant. The tests of the proposed washing mixture in the conditions of the operating plant for the production of styrene showed its high efficiency.

Pyrolysis of end-of-life polystyrene in a pilot-scale reactor: Maximizing styrene production

Chemical recycling of polystyrene (PS) via pyrolysis is of great industrial, and academic interest, with styrene being the primary product of interest. To identify the optimal process conditions, the pyrolysis of end-of-life PS was studied in a pilot-scale unit consisting of an extruder, and a continuous stirred tank reactor (CSTR). The PS was pyrolyzed with continuous feeding at a pressure range from 0.02 to 1.0bara, and a temperature range from 450 to 600 °C, giving primarily styrene, other mono-aromatics, and oligomers. The comprehensive two-dimensional gas chromatography (GC × GC) coupled with flame ionization detector (FID), and time-of-flight mass spectrometer (ToF-MS) as well as GC with thermal conductivity detector (TCD) were used to characterize the liquid, and gaseous products exhaustively.The styrene yield increased from 36 wt% at 1.0bara, and 450 °C to 56 wt% at 0.02bara, and 550 °C. Working under a vacuum enhanced the styrene recovery at all corresponding temperature levels. The yield of benzene, toluene, ethylbenzene, and xylene (BTEX) increased from 4 wt% at 450 °C, and 0.02 bara to 17 wt% at 450 °C, and 1.0 bara. The experimental results have been used in a mathematical model that can explain the combined effect of temperature, and pressure on the yield of the primary products. The present work illustrates the potential of a continuous pyrolysis process for end-of-life PS, and paves the way for this technology to be rapidly transferred from mere laboratory use to industrial processes in the circular (petro-) chemical industry.

Styrene Recovery from the Pyrolysis of Polystyrene Waste Using Bentonite and Natural Zeolite Catalyst

Polystyrene is a type of plastic that is widely used in daily life. It is applied for decoration, food packaging, and electronic packaging process. However, the use of polystyrene has become a problem for the environments because its properties are difficult to be degraded by nature. Pyrolysis method can be regarded as one of the environmentally friendly methods for recycling polystyrene waste. This research aims to investigate the effect of bentonite and natural zeolite catalyst on the pyrolysis of polystyrene. The experiment was carried out in a batch process. The pyrolysis process consists of a cylindrical reactor with electrical heater, a condenser, and a liquid product container. About 100 grams of polystyrene material was pyrolysis per batch. Catalysts used in the variation of 0%, 10%, 15%, 20%, and 25% of polystyrene. The liquid product was collected in 60 minutes and weighed. The composition of the liquid product was determined by gas chromatography. Polystyrene pyrolysis utilizes bentonite and natural zeolite as the catalyst. It produces benzene, toluene, ethylbenzene, styrene, and isopropyl benzene as the liquid product, and polystyrene residue as a solid product. Among the catalyst studied, bentonite is found to be the most efficient and increase the styrene selectivity (30.28 wt%) significantly at a reaction temperature of 400°C in comparison to the natural zeolite catalyst.

Microwave pyrolysis of polystyrene and polypropylene mixtures using different activated carbon from biomass

In this study, microwave pyrolysis was experimented with mixed types of plastic waste. Two different plastic wastes polystyrene waste (PSW) and polypropylene waste (PPW) were used as feedstock. Carbon and activated carbon were synthesized from different biomass; rice husk (RH), corn husk (CH) and coconut sheath (CS) respectively which are used as microwave susceptors. The effect of impregnation on product yields was studied. Microwave pyrolysis at 900 W and with a polymer to an absorbent ratio of 10:1, produced the highest oil yield of 84.30 wt% when coconut sheath activated carbon (CSAC) was used as an absorbent. The reaction time was 10 min for the complete decomposition of polymer mixtures. Oil properties were determined and a high calorific value of 46.87 MJ kg−1 was obtained. These properties were compared to conventional fuel properties and the product oil has a density of 0.76 g ml−1 and viscosity of 2.4 cSt which is an equivalent fraction obtained to that of gasoline. Product oil has a styrene recovery of 67.58% from microwave pyrolysis. The results demonstrate that, microwave pyrolysis has a great potential for energy recovery from mixed plastic waste and the use of agricultural residues as absorbents enhanced the production efficiency of the process.

Enhanced production of styrene by engineered Escherichia coli and in situ product recovery (ISPR) with an organic solvent

BackgroundStyrene is a large-volume commodity petrochemical, which has been used in a wide range of polymer industry as the main building block for the construction of various functional polymers. Despite many efforts to produce styrene in microbial hosts, the production titers are still low and are not enough to meet the commercial production of styrene.ResultsPreviously, we developed a high l-phenylalanine producer (E. coli YHP05), and it was used as a main host for de novo synthesis of styrene. First, we introduced the co-expression system of phenylalanine-ammonia lyase (PAL) and ferulic acid decarboxylase (FDC) genes for the synthesis of styrene from l-phenylalanine. Then, to minimize cell toxicity and enhance the recovery of styrene, in situ product recovery (ISPR) with n-dodecane was employed, and culture medium with supplementation of complex sources was also optimized. As a result, 1.7 ± 0.1 g/L of styrene was produced in the flask cultures. Finally, fed-batch cultivations were performed in lab-scale bioreactor, and to minimize the loss of volatile styrene during the cultivation, three consecutive bottles containing n-dodecane were connected to the air outlet of bioreactor for gas-stripping. To conclude, the total titer of styrene was as high as 5.3 ± 0.2 g/L, which could be obtained at 60 h.ConclusionWe successfully engineered E. coli strain for the de novo production of styrene in both flask and fed-batch cultivation, and could achieve the highest titer for styrene in bacterial hosts reported till date. We believe that our efforts in strain engineering and ISPR strategy with organic solvent will provide a new insight for economic and industrial production of styrene in a biological platform.

Decalin Dissolving Method for Recover of Styrene –Butadiene Rubber from Scrap Tires

Decalin, a hydrocarbon industrial solvent was used for the recovery of Styrene- Butadiene Rubber (SBR) from grind scrap truck tires using chemical dissolving method. The applied technique is easy, simple and depends on available materials. The method depends mainly on steeping the scrap tires grind into decalin at 50?C for one month. Then the process was followed by boiling of the formed thick black solution (198°C) for two hours. The formed elastic rubber material will be reclaimed by precipitation in methanol. The recovered rubber was characterized using FTIR spectroscopy and XRD analyses. The pattern of the recovered material shows broad maxima of SBR with the absence of XRD peaks of carbon black and almost all the other tire manufacturing additives. The thermal characteristics of the reclaimed rubber have been investigated by TGA, DTG and DSC analyses and were found to be close to those of thermal properties of SBR polymer. The SEM image has shown non-crystalline morphological surface of the recovered rubber with cohesive elastomeric properties.

Styrene production from a biomass-derived carbon source using a coculture system of phenylalanine ammonia lyase and phenylacrylic acid decarboxylase-expressing Streptomyces lividans transformants

To produce styrene from a biomass-derived carbon source, Streptomyces lividans was adopted as a host strain. The gene encoding ferulic acid decarboxylase from Saccharomyces cerevisiae (FDC1) was introduced into S.lividans, and the resulting S.lividans transformant successfully expressed FDC1 and converted trans-cinnamic acid (CA) to styrene. A key factor in styrene production using microbes is the recovery of volatile styrene. In the present study, we selected polystyrene resin beads XRD-4 as the absorbent agent to recover styrene produced using S.lividans transformants, which enabled recovery of styrene from the culture broth. For styrene production from biomass-derived carbon sources, S.lividans/FDC1 was cultured together with S.lividans/p-encP, which we previously reported as a CA-producing S.lividans strain. This coculture system combined with the recovery of styrene using XAD-4 allowed the production of styrene from glucose, cellobiose, or xylo-oligosaccharide, respectively.

Effective reclamation of vent gas in ethylbenzene dehydrogenation by coupling multi-stage circle absorption and membrane units

Ethylbenzene catalytic dehydrogenation can generate a large amount of hydrogen. Its vent gas is attractive with hydrogen content higher than 75 mol%. Nevertheless, styrene remaining in the vent gas is highly active to polymerize into oligomers, the gradual accumulation of which is harmful to hydrogen separation equipments. In this work, an integral separation process including absorption and membrane units is established to overcome this challenge. Absorption unit running with fresh ethylbenzene as the absorbent is proposed to deeply remove styrene, the residual content of which is reduced to less than 10 ppm. Thereafter, the generation and accumulation of styrene oligomers is restrained strictly to protect hydrogen separation equipments. Furthermore, the custom-designed absorption tower with a multi-stage cycle structure is used to reasonably improve styrene content in the used ethylbenzene at tower bottom, in the interest of reducing styrene recovery expense. For a 100 kt/a styrene plant with the vent gas flow rate up to 3180 N m3/h, a 5-stage tower is designed, which is 0.5 m in diameter, 5.0 m in height, and about 3.0 m in the total packing height of 25-mm metal Intalox saddles. Flow rates of liquids in the tower and the recycle routes are 1.19 m3/h and 1.05 m3/h, respectively. Finally, compressor and membrane for hydrogen recovery are optimized simultaneously with gross profit as the criterion. For compressor, its duty and outlet pressure are 520 kW and 1.85 MPa, respectively. For membrane separation unit, its area and permeation stage cut are 460 m2 and 0.84, respectively. According to the simulation research, this integrated system can behave excellently with an annual recovery of 162 ton styrene, 281 ton aromatic hydrocarbons and 2.1 × 107 N m3 hydrogen, with a gross profit up to 5.1 × 106 US dollars per year.

α-甲基苯乙烯质量攻关技术研究

吉林石化公司苯酚丙酮装置中设计有一套α-甲基苯乙烯回收单元，由于2001改造时对原有精馏塔进行利旧使用，且工艺流程设计不合理导致生产的α-甲基苯乙烯产品存在纯度低、颜色发黄等质量问题，严重影响了α-甲基苯乙烯作为产品销售。本项目在流程模拟研究和实验室研究的基础上，重新设计了工艺流程，提出改造方案，在保持主体设备不动的前提下，采用脱轻塔和成品塔均增设侧线采出的方式，成功地解决了α-甲基苯乙烯产品质量问题。 A set of alpha methyl styrene recovery unit is designed in the phenol acetone plant of Jilin Petro-chemical Co. In 2001, the transformation of the original rectification tower for the use of the old, and unreasonable process design resulted in that the production of alpha methyl styrene products had quality problem, such as purity is low, color is yellow and so on, which had serious impact on the alpha methyl styrene as product sales. In this project, based on a process simulation research and laboratory research, we redesign the process and put forward the reform plan. Under the premise of keeping the main equipment unchanged, using the way of light off tower and finished tower being added with the sidestreams, the alpha methyl styrene production quality issue is successfully solved.

Styrene recovery from polystyrene by flash pyrolysis in a conical spouted bed reactor

Continuous pyrolysis of polystyrene has been studied in a conical spouted bed reactor with the main aim of enhancing styrene monomer recovery. Thermal degradation in a thermogravimetric analyser was conducted as a preliminary study in order to apply this information in the pyrolysis in the conical spouted bed reactor. The effects of temperature and gas flow rate in the conical spouted bed reactor on product yield and composition have been determined in the 450–600°C range by using a spouting velocity from 1.25 to 3.5 times the minimum one. Styrene yield is strongly influenced by both temperature and gas flow rate, with the maximum yield being 70.6wt% at 500°C and a gas velocity twice the minimum one.

Enhanced styrene recovery from waste polystyrene pyrolysis using response surface methodology coupled with Box–Behnken design

A work applied response surface methodology coupled with Box–Behnken design (RSM-BBD) has been developed to enhance styrene recovery from waste polystyrene (WPS) through pyrolysis. The relationship between styrene yield and three selected operating parameters (i.e., temperature, heating rate, and carrier gas flow rate) was investigated. A second order polynomial equation was successfully built to describe the process and predict styrene yield under the study conditions. The factors identified as statistically significant to styrene production were: temperature, with a quadratic effect; heating rate, with a linear effect; carrier gas flow rate, with a quadratic effect; interaction between temperature and carrier gas flow rate; and interaction between heating rate and carrier gas flow rate. The optimum conditions for the current system were determined to be at a temperature range of 470–505°C, a heating rate of 40°C/min, and a carrier gas flow rate range of 115–140mL/min. Under such conditions, 64.52% WPS was recovered as styrene, which was 12% more than the highest reported yield for reactors of similar size. It is concluded that RSM-BBD is an effective approach for yield optimization of styrene recovery from WPS pyrolysis.

SPE–GC–MS for the sampling and determination of unmetabolized styrene in urine☆

The urinary excretion of unmetabolized styrene can be a very good indicator for biomonitoring styrene in occupationally exposed people. The use of a new urine sampling system, involving a solid-phase extraction cartridge, offers several advantages for determining styrene. The advantages are especially related to the pre-analytical phase of styrene determination, which may be influenced by many variables. The effect on styrene recovery of sorbent type, eluting solvent, elution volume, elution flow-rate, and the addition of methanol to the washing solvent, was evaluated by experimental design methodology. As a result, Oasis HLB cartridges were selected for urine sampling, as well as 1.5 mL of ethyl acetate at 0.5 mL/min for eluting the retained styrene. These conditions were then applied to the validation of the solid-phase extraction combined with GC-MS method for the sampling and analysis of unmetabolized styrene in urine. The overall uncertainty was in the 12-22% range and the limit of detection was 2.2 microg/L for a 4 mL urine sample. The stability of styrene has been studied both in cartridges and in vials under different storage periods. After 1 month period the styrene stored on cartridges at room temperature remained stable, whereas this is not the case for styrene recovery from vials. The results obtained indicate that on-site solid-phase extraction of urine can provide a simple, accurate and reproducible sampling and analytical method for the biomonitoring of styrene in urine.

Reaction mechanism of styrene monomer recovery from waste polystyrene by supercritical solvents

The degradation of polystyrene in supercritical benzene, toluene, ethylbenzene and p-xylene was studied at 310–370 °C, 4.0–6.0 MPa using a novel fast process. Supercritical degradation has unique properties such as excellent heat and mass transfer. By using this technique, polystyrene has been successfully depolymerised into monomer, dimer and other products in a very short reaction time with high conversion. Toluene used as supercritical solvent was more effective than other solvents such as benzene, ethylbenzene and p-xylene for the recovery of styrene from polystyrene, though the conversions of polystyrene were similar in all the above solvents. The highest yield of styrene obtained from polystyrene in supercritical toluene at 360 °C for 20 min reached 77 wt.%. The reaction mechanism consists of depolymerisation of polystyrene and secondary reactions due to closed system. This study indicated that different supercritical solvents affected these two processes differently.

Characterization of Styrene Recovery from the Pyrolysis of Waste Expandable Polystyrene

Catalytic and thermal degradation of waste expandable polystyrene (WEPS) have been studied in a semi-batch reactor with continuous flow of nitrogen to achieve greater oil yield and maximize styrene...

Measurement of styrene-7,8-oxide and other oxidation products of styrene in air.

Styrene-7,8-oxide (SO) is generated at low concentrations from the oxidation of styrene during the processing of reinforced plastics. Since exposure to SO has important health implications, we developed air sampling and analytical methods to measure low levels of airborne SO in the presence of styrene and its other oxidation products, namely phenylacetaldehyde (PAA) and acetophenone (AP). Both active and passive air monitors were used. The active sampling method, which employed adsorption on Tenax, was suitable for measuring SO, PAA and AP but had limited capacity for styrene due to breakthrough. The passive monitor employed a carbon adsorbent and was suitable for measurement of styrene and SO but not PAA and AP due to poor recovery. After sampling, the analytes were extracted from the adsorbents with ethyl acetate and measured by gas chromatography with flame ionization detection or mass spectrometry. By maintaining the injection port at 70 degrees C, the thermal rearrangement of SO to PAA was minimized. Recovery of styrene and SO from the passive monitor depended upon loading and was corrected by linearization of the Freundlich isotherm. The limits of detection for SO, PAA, and AP were 0.2 ppb using the active monitor, and for SO was 1 ppb using the passive monitor. The sampling precision for SO (RSD from personal measurements) was 5.0% for the passive monitor and was 13.4% for the active monitor over a range of exposures from 5-150 ppb. The corresponding precision for styrene was 5.3% for the passive monitor for levels ranging from 1.2 to 104 ppm. Measurements of 235 personal exposures with the active monitor in 12 facilities manufacturing fiberglass-reinforced plastics (FRP) showed that levels of AP and PAA were below 7.8 ppb and 5 ppb, respectively. In contrast, SO averaged 30.4 ppb (SE=2.4) in these FRP facilities, ranging from below 0.2 ppb to 190 ppb. The active monitor was also used to detect airborne SO at levels of approximately equals 1 ppb in one facility manufacturing styrene butadiene rubber, suggesting that SO is generally present during the polymerization of styrene. Personal passive monitoring in the 12 FRP facilities (n = 657) revealed mean concentrations of styrene ranging between 1.8 and 55.4 ppm, and for SO between 1.7 and 62.6 ppb. The ratio of the mean styrene level to the mean SO level varied between 449:1 and 1,635:1 among the 12 FRP facilities.

Hydrous pyrolysis of silica-supported polystyrene

Thermal degradation of polystyrene has been studied in the presence of water under subcritical conditions (hydrous pyrolysis). The experiments were performed in closed systems under inert atmosphere, in the temperature range of 300–320°C, for 1–24 h. The results showed that the presence of water increases the yields of the volatile products, mainly in the first steps of the pyrolitic process, with a higher selectivity of monomer. In order to improve the effective phase contact between water and the polymer during the degradation, hydrous pyrolysis runs have been carried out on silica-supported polystyrene. Some of these experiments were performed using a stirred reactor. Under these conditions, the above effects appeared to be greatly emphasized. Qualitative and quantitative analyses of the degradation products have been reported for the series of runs investigated. The best recovery of styrene has been achieved at 320°C and 8 h, being close to 71%. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2291–2298, 1998

New chemical recycling methodologies: Hydrous pyrolysis to recover monomers from polyolefins

AbstractThermal degradation of polystyrene has been investigated in the presence of water under subcritical conditions (hydrous pyrolysis). The experiments were carried out in closed systems under inert atmosphere, in the temperature range 300–350 °C, at pressures up to 180 atm, for 1–120 h. The results showed that the presence of water increases the yields of volatile products, mainly in the first steps of the pyrolytic process, with a high selectivity in the monomer. In order to improve the phase contact between water and polymer during the pyrolysis, some runs have been carried out on silica‐supported polystyrene and using a stirred reactor. Under these conditions, the above effects appeared to be greatly enhanced. The best recovery of styrene, close to 71%, has been achieved at 320 °C and 8 h.

Influence of dissolved gases in the dynamic headspace analysis of styrene and other volatile organic compounds and improvement of their determination

The on-line purge and trap dynamic headspace technique (PTI) was optimized for styrene. High-boiling volatiles such as styrene were efficiently desorbed from oil and from oil—water matrices. The effects governing the desorption were identified by comparison with an off-line procedure. The recovery of styrene depends dramatically on the amount of fat and on the desorption temperature. For oil-water systems, the aqueous phase had to be saturated with both sodium chloride and carbon dioxide; with PTI, no desorption occurs if the sample is initially degassed; regassing improved desorption, carbon dioxide giving the best results.