38f29fc1-dc9a-4835-b8a4-ed4e1ec20ff7Benzeneproduction mix, at plantMaterials productionPlasticsDisclaimer: The LCI and LCIA results of this dataset can vary from the published Eco-profile on PlasticsEurope website due to the conversion of the original LCI to an ILCD compliant LCI, and some updates of characterization factors used in the Eco-profile since the time of the publication. This was done in agreement with PlasticsEurope.0EU27 including Norway"Benzene is commercially produced based on three different feedstocks:
- Pyrolysis gasoline, a side product of thermal cracking (steam cracking) of hydrocarbons (e.g. naphtha, gas oil, ethane, propane, butanes, natural gas liquids)
- Reformate, a product of catalytic reforming of naphtha
- Light Oil, a condensate fraction of coke oven gas from coal pyrolysis
Additionally, the three aromatics can be chemically transferred into each other by means of transalkylation and disproportionation reactions (for example toluene to benzene and xylenes).
In Europe (EU27) benzene is mainly produced via pyrolysis gasoline and reformate. Since in Europe only 5 % of the BTX aromatics are produced from coke oven gas, this production route is not considered in dataset.
Raw pyrolysis gasoline has to be hydrotreated. The further processing steps of hydrotreated pyrolysis gasoline and reformate are basically identical.
The feedstock (either hydrotreated pyrolysis gasoline or reformate) is fractionated in a first distillation column into a benzene/toluene cut, which contains also the nonaromatic compounds, and into the higher boiling xylenes (including ethylbenzene and styrene) and higher aromatics fraction. Benzene and toluene are separated from the nonaromatics (raffinate) by solvent extraction (liquid-liquid extraction).
In a transalkylation/disproportionation unit, overhead toluene can be converted into additional xylenes. For transalkylation, higher aromatics (e.g. trimethylbenzenes) are co-fed with toluene to produce only xylenes. During disproportionation, two toluene molecules react to form one molecule of benzene and xylenes, respectively.
The xylenes and higher aromatics obtained at the bottom of the feed splitter column together with the xylenes produced in the transalkylation/disproportionation unit are charged to a xylene column. This fractionation unit is designed to either completely separate the xylenes from higher aromatics or to recover also a part of o-xylene in the bottoms. In the latter case, o-xylene can be obtained as product after another distillation step. Higher aromatics (C9+) are either used in toluene transalkylation or blended into the gasoline pool.
The xylenes from the top of the xylene column are fed to the so-called xylene loop, consisting of a p-xylene extraction unit and a xylene isomerisation unit. In the first unit high purity p-xylene is extracted from the equilibrium xylene mixture either by crystallization or by adsorptive separation. The remaining xylene mixture (containing also ethylbenzene and styrene) is fed to an isomerisation unit where a near-equilibrium distribution of xylene isomers is re-established, meaning that new p-xylene is formed from the remaining o- and m-xylenes. The catalyst used here also isomerizes ethylbenzene selectively to xylene isomers in their equilibrium ratio. Hydrogen is added to the isomerisation unit to prevent hydrogenolysis of the aromatics on the metal sites. After separation from light by-products (light ends (methane and hydrogen), benzene, toluene) through fractionation and from unsaturated components the mixed xylenes (and by-product C9+-aromatics) are recycled to the xylene column."LCI resultOtherno extrapolation90.07,700 Kt in 2010 (share of APA members is at least 90% of European production)literature values based on European company surveys & European statisticsnoneNo statementexternal review passedMersiowsky I., Dr.-Ing.The goal and scope of this Eco-profile study was confirmed to be a European production average of the following polymer precursors: benzene, toluene, and ortho-, para-, and mixed xylenes (BTX). The geographical scope includes the EU 27 member states and Norway. Benchmarking data for 50 European steam cracker units were complemented by a desktop study of upstream operations (extraction, refinery), aromatics separation unit, and alternative routes (catalytic reformer, hydrodealkylation). The technological scope probably differs somewhat from the previous versions of the BTX Eco-profiles published by PlasticsEurope which had presumably been limited to catalytic reforming, but were insufficiently transparent on this issue.
The main data source used for this study was a validated confidential report by the petrochemical industry (APPE) under the European Emission Trading Scheme (ETS) on energy use and CO2 emissions of European steamcracking operations. Other processes, including refinery, catalytic reformer, and hydr0dealkylation, were derived from proprietary models (developed by the practitioner IFEU through various petrochemical industry projects). Further, publicly available literature data were used. The review confirmed that, despite no primary data was collected, the data used are applicable, up-to-date, and modelled with a view to internal consistency. The temporal scope was confirmed to be 2010 as reference year and valid at least until 2014 in view of the slow technological changes.
The following aspects were subject to particular scrutiny by the review panel:
• The shares of the alternative routes: extraction from pyrolysis gasoline, catalytic reforming of naphtha, HDA of toluene, coking and HDA of other aromatics;
• the modelling of raffinate (saturated hydrocarbons) as by-product;
• the differences in specific resource use and emissions assigned to the various BTX;
• the consistent and justifiable use of allocation methods;
• plausibility checks of calculations along the productions chains.
A review meeting between the LCA practitioner and the reviewers was held, including a model and database review, and spot checks of data and calculations. The results are thus held to be representative and reliable for the specified production routes. It is noteworthy that, compared with previous studies under the PlasticsEurope Eco-profiles programme, the results for benzene and mixed xylenes have changed notably:
• The previous edition of the Eco-profiles for cracker products apparently used a mass allocation of energy demand and emissions of the steam cracking process to all cracker output streams (thus lowering specific burdens), not only to the HVC as in the present version; from today’s perspective, also to ensure consistency with current industry practice (APPE), the allocation used here is deemed more appropriate.
• According to recent industry data (APPE), benzene is predominantly (approx. 60%) produced from pygas, whereas other aromatics are predominantly (>70%) produced from reformate. Since the pygas route has higher burdens than the reformer route, indicators for benzene have increased.
• Conversely, mixed xylenes were shown to require less steam for separation than o- and p-xylene. As a result, the indicators for mixed xylenes have decreased.
• It is noteworthy that fuel-grade by-products, specifically raffinate (saturated hydrocarbons), were calculated with their calorific value and with their upstream burdens (oil extraction, transport and refining), but no process-related environmental impacts were assigned to them. Process-related burdens (steamcracking, aromatics separation) were only allocated to the high-value BTX compounds.
• The overall levels of greenhouse gas emissions of the steam cracker and aromatics units were confirmed to be in line with APPE’s ETS reporting and internal reports. For greenhouse gas emissions, the results of this new version of the Eco-profile are quite in line with the previous versions of 2005 (with the noteworthy exception of benzene and mixed xylenes discussed above).
• Other impact categories changed somewhat in proportion with the process energy requirements. It should be noted, however, that some indicators apparently changed substantially due to life cycle inventory items in the previous version not being specific enough to allow an accurate a posteriori calculation (average characterisation factors applied to unspecified substance flows). In these cases, a comparison with the previous version is strictly speaking not valid.
Further, the review verified that the model and calculations comply with the rules of the PlasticsEurope Eco-profiles methodology and with ISO 14040–14044: the resulting life cycle inventory datasets for benzene, tolu-ene, and o-, p-, and mixed xylenes (BTX) are thus compatible building blocks for use in other Eco-profile calculations.
Review Summary
The Eco-profile of benzene, toluene, and ortho-, para-, and mixed xylenes (BTX) has been validated to appropriately represent current European production of these polymer precursors. The underlying emission data for the steam cracking process are consistent with reports of the petrochemical industry under the European Emission Trading Scheme (ETS). Other processes, including refinery, catalytic reformer, and hydr0dealkylation were derived from project and literature data and modelled with a view to internal consistency. The results are thus held to be representative and reliable for the specified production routes.
Reviewer Names and Institutions
Chair: Dr.-Ing. Ivo Mersiowsky – Business Line Manager, Sustainability Leadership, DEKRA Consulting GmbH, Stuttgart, Germany
Co-reviewer: Dr. Martin Patel – Copernicus Institute of Sustainable Development, Utrecht University, Utrecht, The Netherlands
Thömmes, T.2022-03-01T00:00:00.000ILCD format 1.1Thömmes, T.2022-03-01T00:00:00.00000.00.001Data set finalised; entirely publishedEco-profiles and Environmental Product Declarations of the European Plastics Manufacturers: Benzene,trueFree of charge for all users and usesGaBi (source code, database including extension modules and single data sets, documentation) remains property of Sphera Solutions GmbH. Sphera Solutions GmbH delivers GaBi licenses comprising data storage medium and manual as ordered by the customer. The license guarantees the right of use for one installation of GaBi. Further installations using the same license are not permitted. Additional licenses are only valid if the licensee holds at least one main license. Licenses are not transferable and must only be used within the licensee's organisation. Data sets may be copied for internal use. The number of copies is restricted to the number of licenses of the software system GaBi the licensee owns. The right of use is exclusively valid for the licensee. All rights reserved.BenzeneOutput1.01.00.000Mixed primary / secondaryUnknown derivationvaluable