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technologyComment of cyclohexane production (RER, RoW): Over 90 % of all cyclohexane is produced commercially by hydrogenation of benzene. A small amount is produced by superfractionation of the naphtha fraction from crude oil. Naturally occurring cyclohexane can be supplemented by fractionating methylcyclopentane from naphtha and isomerizing it to cyclohexane. Hydrogenation of benzene: Benzene can be hydrogenated catalytically to cyclohexane in either the liquid or the vapor phase in the presence of hydrogen. Several cyclohexane processes, which use nickel, platinum, or palladium as the catalyst, have been developed. Usually, the catalyst is supported, e.g., on alumina, but at least one commercial process utilizes Raney nickel. Hydrogenation proceeds readily and is highly exothermic (Δ H500K = – 216.37 kJ/mol). From an equilibrium standpoint, the reaction temperature should not exceed 300 °C. Above this, the equilibrium begins to shift in favor of benzene so that high-purity cyclohexane cannot be produced. As a result of these thermodynamic considerations, temperature control of the reaction is critical to obtaining essentially complete conversion of benzene to cyclohexane. Temperature control requires economic and efficient heat removal. This has been addressed in a number of ways by commercial processes. The earlier vapor-phase processes used multistage reactors with recycle of cyclohexane as a diluent to provide a heat sink, staged injection of benzene feed between reactors, and interstage steam generators to absorb the exothermic heat of hydrogenation. In the 1970s processes have been developed that use only one reactor or a combination of a liquid-and a vaporphase reactor. The objectives of the later processes were to reduce capital cost and improve energy utilization. However, all of the commercial processes have comparably low capital cost and good energy efficiency. In the vapor-phase process with multistage reactors in series, the benzene feed is divided and fed to each of the first two reactors. Recycled cyclohexane is introduced to the first reactor along with hydrogen. The recycled cyclohexane enables higher conversion in the reactors by absorbing part of the heat of hydrogenation. Steam generators between the reactors remove the heat of hydrogenation. The outlet temperature of the last reactor is controlled to achieve essentially 100 % conversion of benzene to cyclohexane. The effluent from the last reactor is cooled, and the vapor and liquid are separated. Part of the hydrogen-rich vapor is recycled to the first reactor, and the rest is purged to fuel gas or hydrogen recovery facilities. The liquid from the separator goes to a stabilizer where the overhead gas is sent to fuel gas; the remaining material is cyclohexane product, part of which is recycled to the first reactor. In the process with liquid- and vapor-phase reactors, benzene and hydrogen are fed to the liquid-phase reactor, which contains a slurry of finely divided Raney nickel. Temperature is maintained at 180 – 190 °C by pumping the slurry through a steam generator and by vaporization in the reactor. Roughly 95 % of the benzene is converted in this reactor. The vapor is fed to a fixed-bed reactor where the conversion of benzene is completed. The effluent from the fixed-bed reactor is processed as described previously for the vapor-phase process. Benzene hydrogenation is done typically at 20 – 30 MPa. The maximum reactor temperature is limited to ca. 300 °C so that a typical specification of < 500 mg/kg benzene and < 200 mg/kg methylcyclopentane in the product can be achieved. This is necessary because of the thermodynamic equilibrium between cyclohexane – benzene and cyclohexane – methylcyclopentane. Actually, equilibrium strongly favors methylcyclopentane, but the isomerization reaction is slow enough with the catalysts employed to avoid a problem if the temperature is controlled. The hydrogen content of the makeup hydrogen has no effect on product purity but it does determine the makeup, recycle, and purge gas rates. Streams with as low as 65 vol % hydrogen can be used. Carbon monoxide and sulfur compounds are catalyst deactivators. Both can be present in the hydrogen from catalytic naphtha reformers or ethylene units, which are typical sources of makeup hydrogen. Therefore, the hydrogen-containing stream is usually passed through a methanator to convert carbon monoxide to methane and water. Prior to methanation, hydrogen-containing gas can be scrubbed with caustic to remove sulfur compounds. Commercial benzene contains less than 1 mg/kg sulfur. In some cases, the recycle gas is also scrubbed with caustic to prevent buildup of hydrogen sulfide from the small amount of sulfur in the benzene. With properly treated hydrogen and specification benzene, a catalyst life in excess of three years can be achieved easily in fixed-bed reactors that use noble-metal catalysts supported on a base. The catalyst in the process that uses Raney nickel in suspension is reported to have a typical life of about six months before it must be replaced. Reference: Campbell, M. L. 2011. Cyclohexane. Ullmann's Encyclopedia of Industrial Chemistry.
technologyComment of rape oil mill operation (Europe without Switzerland, RoW): Typical oil mill designed for rape oil solvent extraction, with pre-pressing of rape seeds, European context.
technologyComment of processing of anode slime from electrorefining of copper, anode (GLO): Based on typical current technology. Anode slime treatment by pressure leaching and top blown rotary converter. Production of Silver by Möbius Electrolysis, Gold by Wohlwill electrolysis, copper telluride cement and crude selenium to further processing. technologyComment of selenium production (RER, RoW): Production from selenium is based on simplified roasting process with sodium carbonate. The inventory is based on stoechiometric calculations, according to the following equations: 2 X-Se + 2 Na2CO3 + 3 CO2 -> 2 Na2O4Se + 2 CO2 + 2 X (with X = compounds that were connected to Se - e.g. Cu2, CuAg, ....) 2 Na2O4Se + 4 HCl -> 2 H2O3Se + 4 NaCl + O2 2 H2O3Se + 2 SO2 -> 2 Se + 2 H2SO4 + O2 A surplus input of 25% is assumed. The air emissions occurring from the process are estimated to 0.2% of the raw material input. The remaining amount of unreacted raw materials is assumed to leave the production process to 95% as a solid waste and to 5% in the wastewater. Further it is assumed that this wastewater is treated in an internal wastewater plant. The carbonate is dissolved in the water and not shown anymore in the dataset. Sodium and chloride are assumed to be neutralized within the waste water treatment plant, leading to emissions of Cl- and Na+ in the water outflow. Sodium dioxide will be reacted into sulphuric acid and therefore leads to emissions of SO42- in the water outflow.
technologyComment of dimethyl carbonate production (RER): Dimethyl carbonate has been historically produced through the reaction of phosgene and methanol. Because of the toxicity of phosgene, a greener route of production has been developed (Tundo and Selva 2002). Today it is mostly produced through the reaction of ethylene or propylene carbonate with methanol. This activity models the production of dimethyl carbonate as the result of the reaction of ethylene carbonate and methanol. Chemical reaction: C3H4O3 + CH3OH -> C3H6O3 + CH2O This inventory representing production of a particular chemical compound is at least partially based on a generic model on the production of chemicals. The data generated by this model have been improved by compound-specific data when available. The model on production of chemicals is using specific industry or literature data wherever possible and more generic data on chemical production processes to fill compound-specific data gaps when necessary. The basic principles of the model have been published in literature (Hischier 2005, Establishing Life Cycle Inventories of Chemicals Based on Differing Data Availability). The model has been updated and extended with newly available data from the chemical industry. In the model, unreacted fractions are treated in a waste treatment process, and emissions reported are after a waste treatment process that is included in the scope of this dataset. For volatile reactants, a small level of evaporation is assumed. Solvents and catalysts are mostly recycled in closed-loop systems within the scope of the dataset and reported flows are for losses from this system. The main source of information for the values for heat, electricity, water (process and cooling), nitrogen, chemical factory is industry data from Gendorf. The values are a 5-year average of data (2011 - 2015) published by the Gendorf factory (Gendorf, 2016, Umwelterklärung, www.gendorf.de), (Gendorf, 2015, Umwelterklärung, www.gendorf.de), (Gendorf, 2014, Umwelterklärung, www.gendorf.de). The Gendorf factory is based in Germany, it produces a wide range of chemical substances. The factory produced 1657400 tonnes of chemical substances in the year 2015 (Gendorf, 2016, Umwelterklärung, www.gendorf.de) and 740000 tonnes of intermediate products. Reference(s): Hischier, R. (2005) Establishing Life Cycle Inventories of Chemicals Based on Differing Data Availability (9 pp). The International Journal of Life Cycle Assessment, Volume 10, Issue 1, pp 59–67. 10.1065/lca2004.10.181.7 Gendorf (2016) Umwelterklärung 2015, Werk Gendorf Industriepark, www.gendorf.de Tundo, P. and Selva, M. 2002. The Chemistry of Dimethyl Carbonate. Acc. Chem. Res. Vol.9, 35, pp. 706–716 For more information on the model please refer to the dedicate ecoinvent report, access it in the Report section of ecoQuery (http://www.ecoinvent.org/login-databases.html) technologyComment of oxidation of methanol (RER): Represents a current cross-section of actual plants in Europe. The inventory is based on 100% formaldehyde production. The inputs and outputs are an average of the Silver and Formox processes. Silver process: Initially, methanol is dehydrogenated and subsequently there is combustion of hydrogen overall resulting in the production of formaldehyde and water. The raction takes place with air over a crystalline silver catalyst. Formox process: Methanol is directly oxidized by air over a metal oxide catalyst at a temperature of 470 °C. excess heat is removed with an oil-transfer medium. The product gases are cooled, absorbed in water, and an aqueous 37% formaldehyde solution is obtained. (Wells, 1999) References: G. Margaret Wells, “Handbook of Petrochemicals and Processes”, 2nd edition, Ashgate, 1999 Althaus H.-J., Chudacoff M., Hischier R., Jungbluth N., Osses M. and Primas A. (2007) Life Cycle Inventories of Chemicals. Final report ecoinvent data v2.0 No. 8. Swiss Centre for Life Cycle Inventories, Dübendorf, CH.
technologyComment of adipic acid production (RER, RoW): This dataset models the production of adipic acid by nitric acid oxidation of a mixture of cyclohexanol and cyclohexanone, which is obtained by oxidation of cyclohexane. Abatement of N2O emissions is assumed to reduce the emissions by 80%. Essentially all production of adipic acid is derived from the nitric acid oxidation of a mixture of cyclohexanone – cyclohexanol (KA mixture). The reactor, controlled at 60 – 80 °C and 0.1 – 0.4 MPa, is charged with the recycled nitric acid stream, the KA feed material, and makeup acid containing 50 – 60 % nitric acid and copper – vanadium catalyst. The reaction is very exothermic (6.280 MJ/kg). Adipic acid is obtained with a yield greater than 90%. Nitrogen oxides, carbon dioxide, and some lower dicarboxylic acids are the major by-products, as well as oxidation products arising from impurities in the KA intermediate. The nitric acid oxidation step produces three major waste streams: an off-gas containing oxides of nitrogen and CO2, water containing traces of nitric acid and organics from the water removal column; and a dibasic acid purge stream containing adipic, glutaric and succinic acids. The production of adipic acid can be represented by the following simplified reaction formula: 0.733 C6H12O + 0.367 C6H10O + 2 HNO3 -> C6H10O4 + N2O + 2 H2O + 7.23 H2 References: Althaus H.-J., Chudacoff M., Hischier R., Jungbluth N., Osses M. and Primas A. (2007) Life Cycle Inventories of Chemicals. ecoinvent report No. 8, v2.0. EMPA Dübendorf, Swiss Centre for Life Cycle Inventories, Dübendorf, CH.
technologyComment of styrene production (RoW): Styrene is mainly produced by the dehydrogenation of ethylbenzene (EBS process) and via ethylbenzene hydroperoxide (POSM process) with propylene oxide as a by-product (James and Castor 2011). This dataset reflects only the dehydrogenation of ethylbenzene (EBS). Close to the entire production of ethylbenzene is produced via the alkylation of ethylene and benzene (Welch et al. 2005). This production route has been used since the mid-nineties (James and Castor 2011). Chemical reaction: C6H6 + C2H4 -> C8H10 C8H10 -> C8H8 + H2 The reaction from ethylbenzene to styrene is reversible. The reaction is endothermic with a heat delta of 600 degrees Celcius and 124.0 kJ/mol (James and Castor 2011). The production of styrene is mostly performed (ca. 75% of production), by running ethylbenzene (the input includes recycled ethylbenzene) through subsequent reactors / reactors beds. Steam is used to dehydrogenate the input product. Steam has been found to ensure a high yield, provide the necessary conditions for the reaction to happen and at the same time cleaning the used catalyst (James and Castor 2011). The use of a catalyst boosts the efficiency of the reaction, otherwise low temperature and low pressure are enough to ensure the reaction but with lower yield. Usual reaction conditions are 620 degrees Celsius combined with very low pressure, this ensures a yield between 88 and 95% (James and Castor 2011). According to James and Castor (2011) one of the most used catalyst for this reaction is composed by 84.3% iron (Fe2O3), 2.4% chromium (Cr2O3), and 13.3% potassium (K2CO3) (James and Castor 2011). The average lifespan of catalysts for this reaction is assumed to be 2 years (James and Castor 2011). The catalyst in not consider significant in terms of emissions for the reaction and it is therefore not included in this dataset and it is assumed to be taken into consideration in the input of chemical factory. The main source of information for the values for water (process and cooling), nitrogen and chemical factory is industry data from Gendorf. The values are a 5-year average of data (2011 - 2015) published by the Gendorf factory (Gendorf, 2016, Umwelterklärung, www.gendorf.de), (Gendorf, 2015, Umwelterklärung, www.gendorf.de), (Gendorf, 2014, Umwelterklärung, www.gendorf.de). The Gendorf factory is based in Germany, it produces a wide range of chemical substances. The factory produced 1657400 tonnes of chemical substances in the year 2015 (Gendorf, 2016, Umwelterklärung, www.gendorf.de) and 740000 tonnes of intermediate products. Reference(s): Hischier, R. (2005) Establishing Life Cycle Inventories of Chemicals Based on Differing Data Availability (9 pp). The International Journal of Life Cycle Assessment, Volume 10, Issue 1, pp 59–67. 10.1065/lca2004.10.181.7 Gendorf (2016) Umwelterklärung 2015, Werk Gendorf Industriepark, www.gendorf.de James, D.H. and Castor, W.M. 2011. Styrene. In Ullmann's Encyclopedia of Industrial Chemistry, Electronic Release, Vol.34, pp.529-544. Wiley-VCH, Weinheim. Welch, V.A. et al. 2005. Ethylbenzene. In Ullmann's Encyclopedia of Industrial Chemistry, Electronic Release, Vol.13, pp.451-464. Wiley-VCH, Weinheim. technologyComment of styrene production (RER): Styrene is mainly produced by the dehydrogenation of ethylbenzene (EBS process) and via ethylbenzene hydroperoxide (POSM process) with propylene oxide as a by-product (James and Castor 2011). This dataset reflects only the dehydrogenation of ethylbenzene (EBS). Close to the entire production of ethylbenzene is produced via the alkylation of ethylene and benzene (Welch et al. 2005). This production route has been used since the mid-nineties (James and Castor 2011). Chemical reaction: C6H6 + C2H4 -> C8H10 C8H10 -> C8H8 + H2 The reaction from ethylbenzene to styrene is reversible. The reaction is endothermic with a heat delta of 600 degrees Celcius and 124.0 kJ/mol (James and Castor 2011). The production of styrene is mostly performed (ca. 75% of production), by running ethylbenzene (the input includes recycled ethylbenzene) through subsequent reactors / reactors beds. Steam is used to dehydrogenate the input product. Steam has been found to ensure a high yield, provide the necessary conditions for the reaction to happen and at the same time cleaning the used catalyst (James and Castor 2011). The use of a catalyst boosts the efficiency of the reaction, otherwise low temperature and low pressure are enough to ensure the reaction but with lower yield. Usual reaction conditions are 620 degrees Celsius combined with very low pressure, this ensures a yield between 88 and 95% (James and Castor 2011). According to James and Castor (2011) one of the most used catalyst for this reaction is composed by 84.3% iron (Fe2O3), 2.4% chromium (Cr2O3), and 13.3% potassium (K2CO3) (James and Castor 2011). The average lifespan of catalysts for this reaction is assumed to be 2 years (James and Castor 2011). The catalyst in not consider significant in terms of emissions for the reaction and it is therefore not included in this dataset and it is assumed to be taken into consideration in the input of chemical factory. The main source of information for the values for water (process and cooling), nitrogen and chemical factory is industry data from Gendorf. The values are a 5-year average of data (2011 - 2015) published by the Gendorf factory (Gendorf, 2016, Umwelterklärung, www.gendorf.de), (Gendorf, 2015, Umwelterklärung, www.gendorf.de), (Gendorf, 2014, Umwelterklärung, www.gendorf.de). The Gendorf factory is based in Germany, it produces a wide range of chemical substances. The factory produced 1657400 tonnes of chemical substances in the year 2015 (Gendorf, 2016, Umwelterklärung, www.gendorf.de) and 740000 tonnes of intermediate products. Reference(s): Hischier, R. (2005) Establishing Life Cycle Inventories of Chemicals Based on Differing Data Availability (9 pp). The International Journal of Life Cycle Assessment, Volume 10, Issue 1, pp 59–67. 10.1065/lca2004.10.181.7 Gendorf (2016) Umwelterklärung 2015, Werk Gendorf Industriepark, www.gendorf.de James, D.H. and Castor, W.M. 2011. Styrene. In Ullmann's Encyclopedia of Industrial Chemistry, Electronic Release, Vol.34, pp.529-544. Wiley-VCH, Weinheim. Welch, V.A. et al. 2005. Ethylbenzene. In Ullmann's Encyclopedia of Industrial Chemistry, Electronic Release, Vol.13, pp.451-464. Wiley-VCH, Weinheim. Certain data points from a company survey by PlasticsEurope (three companies and four production sites).
technologyComment of cryolite production (RER, RoW): Production by the hydrofluoric acid technique. In a first step, alumina trihydrate is leached by hydrofluoric acid - in the second step cryolite is precipitated by adding sodium hydroxide. The overall process yield is of 98%. Inventory bases on stoechiometric calculations. The emissions to air (0.2 wt.% of HF input) and water were estimated using mass balance. technologyComment of cryolite production, from fluosilicic acid (GLO): The main production of cryolite involves hydrofluoric acid or fluosilicic acid. In both cases, the reactants can be combined with a variety of materials, such as Al2O3 · 3 H2O, Al2O3 · x NaOH, NaOH, NaCl, and Na2SO4. During the present reaction, fluosilicic acid is neutralised with sodium hydroxide. Then it reacts with Al2O3 to produce cryolite and silica. The reaction process is shown below: Al2O3 + 2H2SiF6 + 6 NaOH --> 2 Na3AlF6 + 2 SiO2 + 5 H2O It is difficult to predict how much of the cryolite is produced with the present reaction, since many production routes exist. The present inventory serves as an illustration of the cryolite production from fluosilicic acid. The alternative production route with HF is still considered to be the main production route (source: Ullmann encyclopedia, Cryolite, 2005).
technologyComment of natural gas liquids fractionation (GLO): The recovered NGL stream is processed through a fractionation train consisting of up to five distillation towers in series: a demethanizer, a deethanizer, a depropanizer, a debutanizer and a butane splitter. The overhead product from the deethanizer is ethane and the bottom product is fed to the depropanizer. The overhead product from the depropanizer is propane and the bottom is fed to the debutanizer. The overhead product from the debutanizer is a mixture of normal and iso-butane, and the bottom is a C5+ gasoline mixture (pentane in this inventory). A slightly simplyfied fractioning process can be seen in the sketch below. imageUrlTagReplace937d93d2-cfed-4ec9-9363-614415661a5c Source: Thompson S. M., Robertson G. (2011): Liquefied Petroleum Gas, in Ullmanns Encyclopedia of Industrial Chemistry, 7th Edition. technologyComment of natural gas production (CA-AB): Canadian data completed with german data. The uncertainty has been adjusted accordingly. Data used in original data contains no information on technology. technologyComment of natural gas production (RoW): The data describes an average onshore technology for natural gas to 13% out of combined oil gas production. Natural gas is assumed to 20% sour. Leakage in exploitation is estimated at 0.38% and production 0.12%. It is further assumed that about 30% of the produced water is discharged in surface water. Water emissions are differentiated between combined oil and gas production and gas production.
technologyComment of natural gas liquids fractionation (GLO): The recovered NGL stream is processed through a fractionation train consisting of up to five distillation towers in series: a demethanizer, a deethanizer, a depropanizer, a debutanizer and a butane splitter. The overhead product from the deethanizer is ethane and the bottom product is fed to the depropanizer. The overhead product from the depropanizer is propane and the bottom is fed to the debutanizer. The overhead product from the debutanizer is a mixture of normal and iso-butane, and the bottom is a C5+ gasoline mixture (pentane in this inventory). A slightly simplyfied fractioning process can be seen in the sketch below. imageUrlTagReplace937d93d2-cfed-4ec9-9363-614415661a5c Source: Thompson S. M., Robertson G. (2011): Liquefied Petroleum Gas, in Ullmanns Encyclopedia of Industrial Chemistry, 7th Edition. technologyComment of natural gas production (CA-AB): Canadian data completed with german data. The uncertainty has been adjusted accordingly. Data used in original data contains no information on technology. technologyComment of natural gas production (RoW): The data describes an average onshore technology for natural gas to 13% out of combined oil gas production. Natural gas is assumed to 20% sour. Leakage in exploitation is estimated at 0.38% and production 0.12%. It is further assumed that about 30% of the produced water is discharged in surface water. Water emissions are differentiated between combined oil and gas production and gas production.
technologyComment of methylchloride production (WEU): Data refers to actual technology used in the companies included. This leads in total to an average value including all important production routes for this chemical
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