Developing and testing sustainability assessment tools for chemical processes and products:case study on critical rare earth elements

Abstract This thesis work aims to develop sustainability assessment tools for chemical processes, unit operations, catalysts, and products and to test the tools on products containing critical rare earth elements (REEs). This thesis is a part of the study where a Green Chemistry-based Sustainability Assessment Tool (SAT) was developed for the early design phase of chemical production processes. The SAT tool is comprised of indicators selected using the twelve principles of Green Chemistry as guidelines. It was tested on conventional and carbon dioxide-based formic acid production routes. Similarly, a sustainability assessment tool was developed based on the integration of Green Engineering principles and the multi-criteria decision analysis (MCDA) analytical hierarchy method (AHP). The developed tool is suitable for the assessment of catalysts in chemical processes. It was tested in ethanol steam reforming using four nickel (Ni)-catalysts (REEs and non-REEs). The Ni-catalysts were assessed and compared against each other to determine the substitution potential of REEs in catalysts. Thirdly, a Product Sustainability Assessment Tool (PSAT) was developed for assessing the sustainability of products. Here the principles of Green Chemistry, Industrial Ecology, and Green Engineering were used as guidelines in developing the assessment criteria. The developed PSAT tool also incoorporates life cycle impact categories and Circular Economy approach. It takes into account five life cycle stages of a product: design, materials selection, manufacturing, use, and end-of-life. The developed PSAT tool was tested on two 3 MW wind turbine generators; a) a doubly fed inductor generator (DFIG) without an REEs containing permanent magnet and b) a direct-drive Permanent Magnet Synchronous Generator (PMSG) containing REEs. The results obtained from the assessment of ethanol steam reforming catalysts demonstrated that cerium and lanthanum oxide supported catalysts can be successfully substituted with an aluminium oxide supported catalyst while retaining the sustainability performance of the reaction. The results from the sustainability assessment of wind turbine generators revealed that the DFIG turbine had an overall better sustainability impact than the direct-drive PMSG generator.Tiivistelmä Tämän väitöskirjatyön tavoitteena on kehittää kestävyyden arviointimenetelmiä kemiallisten prosessien, yksikköoperaatioiden, katalyyttien ja erilaisten tuotteiden arviointiin sekä testata menetelmiä kriittisiä harvinaisia maametalleja (REEs) sisältävien tuotteiden arviointiin. Väitöskirjatyö on osa tutkimusta, jossa kehitettiin Vihreän kemian periaatteisiin perustuva (Green Chemistry -based) kestävyyden arviointityökalu (SAT), joka soveltuu kemiallisten tuotantoprosessien varhaisen suunnittelun aikaiseen arviointiin. SAT-työkalu koostuu indikaattoreista, jotka valitaan Vihreän kemian kahdentoista periaatteen avulla. SAT-työkalua hyödyntämällä arvioidaan muurahaishapon kahden tuotantoreitin, teollisessa käytössä olevan ja hiilidioksidipohjaisen valmistusreitin, kestävyyttä. Tässä työssä kehitettiin myös Vihreän tekniikan periaatteisiin perustuva (Green Enggineering principles -based) ja katalyyttien kestävyyden arviointiin soveltuva arviointityökalu, joka pohjautuu Aspen Plus -prosessisimulaation, analyyttisen hierarkiamenetelmän (Analytical Hierarchy Method - AHP), min-max-normalisointitekniikan ja Likert-asteikon samanaikaiseen käyttöön. Kehitettyä työkalua testattiin vertailemalla etanolin höyryreformointia neljällä nikkelikatalyytillä, joista kaksi sisälsi ja kaksi ei sisältänyt REE-metalleja. Nikkelikatalyyttien vertailu tehtiin REE-katalyyttien korvausmahdollisuuden määrittämiseksi. Väitöskirjatyössä kehitettiin myös tuotteen kestävyyden arviointimenetelmä (PSAT). Tässä menetelmässä hyödynnetään indikaattoreiden valinnassa vihreän kemian, teollisen ekologian ja vihreän tekniikan periaatteita. PSAT-menetelmään integroitiin myös elinkaariarvioinnin (LCA) avulla saatavat vaikutukset. PSAT-menetelmässä arvioidaan viisi tuotteen elinkaaren vaihetta, jotka ovat tuotteen suunnittelu, materiaalien valinta, valmistus, käyttö ja käytöstä poistuminen. PSAT soveltuu tuotteiden kestävyysarviointiin ja toimii ohjeena vertailtaessa tuotevaihtoehtoja. PSAT-menetelmää käytettiin kahden 3 MW:n tuuliturbiinigeneraattorin eli a) kaksoissyöttöisen kelageneraattorin (DFIG) ilman REE-magneettia ja b) suorakäyttöisen kestomagneettisynkronisen generaattorin (PMSG), jossa on REE-kestomagneetti, kestävyyden arviointiin. Etanolin höyryreformointikatalyyttien arvioinnista saadut tulokset osoittivat, että cerium- ja lantaanioksidikatalyytit voidaan menestyksekkäästi korvata alumiinioksidituetulla katalyytillä säilyttäen samalla reaktioreitin kestävyysominaisuudet. Tuuliturbiinigeneraattoreiden kestävyysarviointien tulokset osoittavat puolestaan, että DFIG-turbiinin kestävyysvaikutus oli kokonaisuutena parempi kuin suoravetoisen PMSG-generaattorin vaikutus

Sustainability assessment of formic acid production:comparison of CO₂ based and conventional processes

Sustainability can be described as a developmental approach whose focus is to integrate economic activity with social security and environmental protection. Sustainability of chemical process involves the use of sustainable practices in the chemical industry. Sustainability assessment describes the methods used for achieving sustainability in industries, it is needed because unsustainable practices can be tracked and corrected and also to track progress made by the company in achieving sustainability. The aim of this thesis was to use a green chemistry based sustainability assessment tool to compare one conventional and two CO₂ utilization routes in order to find the more sustainable way of producing formic acid and to suggest methods for improving the tool. The three routes considered in this work were the conventional route, which was done on a commercial scale. This method of producing formic acid is via methyl formate hydrolysis. The experimental route and the BP patented routes represented CO₂ utilization routes on laboratory scale setting and commercial setting respectively. These methods for producing formic acid involved the hydrogenation of CO₂. Another aim of this thesis was to review some currently used assessment tools related to sustainability. Six currently utilized assessment tools related to sustainability were compared based on their strengths and weaknesses and evaluated. Sustainability assessment was conducted on the three formic acid production routes based on the green chemistry assessment tool using the most important features. Sustainability assessment questionnaire based on the twelve green chemistry principles was used to assess the three formic acid production routes. The strengths and weakness of the green chemistry tool were discussed and recommendations for improving the tool were suggested. One way of improving the tool is to merge it with LCA in order to assess every stage of a product’s life cycle from cradle to grave. The results from the assessment showed that the conventional route was harmful to the environment while the CO₂ utilization routes were beneficial to the environment. The social section of the result showed that both the conventional and CO₂ utilization routes were socially unsustainable and the economic section of the results showed that the conventional and the CO₂ utilization routes were economically viable but the CO₂ utilization routes were more economically viable than the conventional route. Overall, the experimental CO₂ utilization route is the most sustainable way to produce formic acid. It is important that more research will be done on CO₂ utilization method of producing formic acid in order for it to fulfill its potential as a sustainable method

Substitution potential of rare earth catalysts in ethanol steam reforming

Abstract This study suggests the possibility of substituting rare earths containing catalysts in ethanol steam reforming by means of sustainability assessment. Four Ni-catalysts are assessed; two of the Ni-catalysts are rare earths containing catalysts Ni/Al₂O₃-CeO₂and Ni/La₂O₃ while the other two are non-rare earths containing catalysts Ni/Al₂O₃ and Ni/ZnO. The sustainability assessment tool used covers environmental, health and safety and economic indicators in conjunction with a linear scale transformation (Max) normalization technique and an analytical hierarchy method to evaluate the sustainability performance of the catalysts. The sustainability assessment results obtained demonstrated that Ni/Al₂O₃ is the best performing catalysts in terms of the overall sustainability of the ethanol steam reforming reaction. The rare earths containing catalyst supports, i.e. cerium and lanthanum oxides can be successfully substituted with aluminum oxide catalyst support whilst still maintaining the overall sustainability performance of the reaction

Sustainability assessment of products:case study of wind turbine generator types

Abstract This study proposes a product sustainability assessment tool (PSAT) that addresses the environmental, health and safety, social, and economic sustainability aspects from a life cycle perspective. The proposed PSAT uses the principles of Green Chemistry, Industrial Ecology, and Green Engineering as guidelines in the development of its assessment criteria. The developed assessment criteria are expressed as easy-to-answer questions covering the environmental, social, health and safety and economic aspects of sustainability. PSAT also incorporates life cycle assessment impact categories and the Circular Economy approach. PSAT comprises an Excel checklist of a questionnaire with a drop-down list of answers to select from describing the sustainability impact of the assessed product. PSAT serves to highlight the sustainability hotspots in a product’s life cycle. The questionnaire consists of qualitative and quantitative assessment criteria and contains a total of 97 questions, out of which there are 11 design questions, 22 materials selection questions, 31 manufacturing questions, 24 use questions, and 9 end-of-life questions. The PSAT scoring system enables users to compare the sustainability performance of their products. PSAT aims to aid users in making informed decisions before purchasing a product based on the information on how the product is designed and what materials it contains, how it was manufactured, how it will perform during its use, and what will happen at the end of its useful life. It also aims to aid product manufacturers and designers in incorporating sustainability into all stages of the product life cycle. The PSAT methodology promotes a holistic view of a product life cycle, including the design, materials selection, manufacturing, use, and end-of-life stage. As a case study, PSAT was used to perform a comparative sustainability assessment of two types of 3 MW rated power wind turbines: a direct-drive permanent magnet synchronous generator (PMSG) and a doubly-fed induction generator with a gearbox (DFIG). The results from the sustainability assessment reveal that the DFIG wind turbine had a better sustainability impact than the direct-drive PMSG in the materials selection, manufacturing, and end-of-life life cycle stages. On the other hand, the direct-drive PMSG had a better sustainability impact than DFIG in the life cycle stages design and use. Overall, DFIG demonstrated a better sustainability impact than the direct-drive PMSG

Recycling and substitution of light rare earth elements, cerium, lanthanum, neodymium, and praseodymium from end-of-life applications:a review

Abstract The light rare earth elements (LREEs) lanthanum, cerium, neodymium and praseodymium are increasingly used in renewable energy technology and are applicable in portable electronic devices, such as phosphors in lightning applications and in catalysis. The extraction of REEs from virgin ores causes environmental degradation. LREEs are considered as critical metals. To overcome the environmental and criticality challenges of LREEs, recycling presents means by which they can be obtained from secondary sources. Presently, the recycling rate of LREEs is still very low. Substitutes of LREEs in most cases are either inferior or still undiscovered. This study investigates the criticality challenges and environmental impacts of producing LREEs from virgin ores. It focuses on LREEs obtainable in selected end-of-life products considered to have significant recycling potential; these include NdFeB magnets, Ni-MH batteries, phosphors in lighting and catalysts. Current recycling technologies, including representative methods and current recycling challenges are also reviewed. Although current recycling technologies have recorded growth, there is still a need for further improvements. The article highlights current LREEs substitution advances and the faced challenges in finding suitable LREEs substitutes. Furthermore, future ways to promote sustainability of LREEs recycling, to improve substitution, and to tackle the criticality challenges of LREEs are proposed

Developing and testing a tool for sustainability assessment in an early process design phase:case study of formic acid production by conventional and carbon dioxide-based routes

Abstract This paper suggests a ‘Sustainability Assessment Tool’ that can be used in early design phases of production processes. “Green Chemistry” principles were considered as a baseline when proposing the sustainability indicators. European chemicals regulations and databases were also applied and used as a baseline in chemicals hazards assessment. The tool is an excel based checklist, with multiple choice answers that are scored based on their severity of impact. This Sustainability Assessment Tool was tested by comparing two formic acid production routes. It is proposed that using the tool as a guideline in the early stages of a chemical process design can provide competitive advantages in research as it provides guidance on the critical target areas of the process that should be further developed. This can further guide researchers and engineers through the piloting and manufacturing stages. In addition it is also expected that the suggested sustainability assessment tool can be used as an educating purpose to foster sustainability in process design work during all the design stages