Carbon dioxide: from waste to resource for methanol-based processes

International audienc

Electronic waste recovery in Finland:consumers’ perceptions towards recycling and re-use of mobile phones

Abstract This paper examines consumers’ awareness and perceptions towards mobile phone recycling and re-use. The results are based on a survey conducted in the city of Oulu, Finland, and analysed in the theoretical framework based on the theories of planned behaviour (TPB) and value-belief-norm (VBN). The findings indicate that consumers’ awareness of the importance and existence of waste recovery system is high; however, awareness has not translated to recycling behaviour. The survey reveals that 55% of respondents have two or more unused mobile phones at homes. The more phones stored at homes, the more often reasons ‘I don’t know where to return’ and/or ‘have not got to do it yet’ were mentioned. This indicates that proximity and the convenience of current waste management system are inadequate in promoting the return of small waste electrical and electronic equipment (WEEE). To facilitate re-use, and the highest level of recovery, consumers will need to be committed to return end-of-use electronics to WEEE collection centres without delays. Further, the supply and demand of refurbished mobile phones do not meet at this moment in Finland due to consumer’s storing habits versus expectations of recent features under guarantee and unrealistic low prizes. The study also points out that, in order to change current storing habits of consumers, there is an explicit need for more information and awareness on mobile phone collection in Finland, especially on regarding retailers’ take-back

End-of-use vs. end-of-life:when do consumer electronics become waste?

Abstract This study focuses on the lifespan of consumer electronics. The article reviews end-of-life terminology in scientific literature and suggests distinguishing end-of-use and end-of-life stages. The question, when electronics become waste, is approached using the concept of a system called PSSP language, which classifies artefacts based on their attributes of purpose, structure, state and performance. It is highlighted that waste as a concept is dynamic; the same thing can be waste or non-waste at different times and places and for different people. Further, the article reviews the impact of storage behavior on the realization of the waste hierarchy, using mobile phones as a case study. Evidence suggests that over half of customers use their mobile phones for only two years, and there is little incentive to keep them in use longer. Surveys also indicate that over half of the customers do not return their phones for reuse or recycling but keep them at home. The article suggests that the three key factors, promoting the storing of an old phone, are the shortness of usage time, perceived residual value of replaced equipment and concerns of personal information security. It is also indicated that memories and the personal attachment to the device contribute to consumers’ storage decision. It is concluded that, to prolong the use of mobile phones, there is a demand for changing consumers attitudes towards the return of electronics for reuse and repair to be more positive

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

Oxidation of dichloromethane over Au, Pt, and Pt-Au containing catalysts supported on γ-Al₂O₃ and CeO₂-Al₂O₃

Abstract Au, Pt, and Pt-Au catalysts supported on Al₂O₃ and CeO₂-Al₂O₃ were studied in the oxidation of dichloromethane (DCM, CH₂Cl₂). High DCM oxidation activities and HCl selectivities were seen with all the catalysts. With the addition of Au, remarkably lower light-off temperatures were observed as they were reduced by 70 and 85 degrees with the Al₂O₃-supported and by 35 and 40 degrees with the CeO₂-Al₂O₃-supported catalysts. Excellent HCl selectivities close to 100% were achieved with the Au/Al₂O₃ and Pt-Au/Al₂O₃ catalysts. The addition of ceria on alumina decreased the total acidity of these catalysts, resulting in lower performance. The 100-h stability test showed that the Pt-Au/Al₂O₃ catalyst was active and durable, but the selectivity towards the total oxidation products needs improvement. The results suggest that, with the Au-containing Al₂O₃-supported catalysts, DCM decomposition mainly occurs via direct DCM hydrolysis into formaldehyde and HCl followed by the oxidation of formaldehyde into CO and CO₂

Ongelmasta hyödyke: hiilidioksidi metanolin ja dimetyylikarbonaatin raakaaineena

International audienc

Evaluation of nanofiltration membranes for the purification of monosaccharides:influence of pH, temperature, and sulfates on the solute retention and fouling

Abstract Furfural, acetic acid, and sulfates are found in the hemicellulose (HMC) fraction of lignocellulosic biomass. Separation of furfural, acetic acid, and sulfates from monosaccharides by four nanofiltration (NF) membranes was evaluated with a model solution of glucose, xylose, furfural, acetic acid, and sulfates. Results showed that Alfa Laval NF99HF is the most promising membrane to purify monosaccharides, with the retentions of xylose (85%), glucose (95%), and with the minimum sulfate retention. pH has the highest impact on the retention of all solutes and there is no significant effect of temperature on the retentions of sulphates and acetic acid. Lower pH and temperature are favored to maximize the monosaccharide retention and to remove acetic acid while retaining more furfural with the monosaccharides. Moreover, fouling tendency is maximized at lower pH and higher temperatures. According to the statistical analysis, the retentions of glucose, xylose, furfural, sulfates, and acetic acid are 95%, 90%, 20%, 88%, and 0%, respectively at pH 3 and 25 °C. The presence of sulfates favors the separation of acetic acid and furfural from monosaccharides

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

Effect of nanoparticle size in Pt/SiO₂ catalyzed nitrate reduction in liquid phase

Abstract Effect of platinum nanoparticle size on catalytic reduction of nitrate in liquid phase was examined under ambient conditions by using hydrogen as a reducing agent. For the size effect study, Pt nanoparticles with sizes of 2, 4 and 8 nm were loaded silica support. TEM images of Pt nanoparticles showed that homogeneous morphologies as well as narrow size distributions were achieved during the preparation. All three catalysts showed high activity and were able to reduce nitrate below the recommended limit of 50 mg/L in drinking water. The highest catalytic activity was seen with 8 nm platinum; however, the product selectivity for N₂ was highest with 4 nm platinum. In addition, the possibility of PVP capping agent acting as a promoter in the reaction is highlighted

Catalytic activity studies of vanadia/silica–titania catalysts in SVOC partial oxidation to formaldehyde:focus on the catalyst composition

Abstract In this work, silica–titania supported catalysts were prepared by a sol–gel method with various compositions. Vanadia was impregnated on SiO₂-TiO₂ with different loadings, and materials were investigated in the partial oxidation of methanol and methyl mercaptan to formaldehyde. The materials were characterized by using N₂ physisorption, X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), X-ray photoelectron spectroscopy (XPS), Scanning transmission electron microscope (STEM), NH₃-TPD, and Raman techniques. The activity results show the high importance of an optimized SiO₂-TiO₂ ratio to reach a high reactant conversion and formaldehyde yield. The characteristics of mixed oxides ensure a better dispersion of the active phase on the support and in this way increase the activity of the catalysts. The addition of vanadium pentoxide on the support lowered the optimal temperature of the reaction significantly. Increasing the vanadia loading from 1.5% to 2.5% did not result in higher formaldehyde concentration. Over the 1.5%V₂O₅/SiO₂ + 30%TiO₂ catalyst, the optimal selectivity was reached at 415 °C when the maximum formaldehyde concentration was ~1000 ppm