Twenty Years of the Polyvinyl Chloride Sustainability Challenges

Intense campaigning pressure on the UK PVC sector up to the late 1990s forced strategic engagement with sustainable development. Simplified outcomes from a detailed, consensus-based analysis by science-based NGO The Natural Step (TNS) took the form of five TNS Sustainability Challenges for PVC published in 2000. UK manufacturing companies initially used these Challenges to direct strategic progress. The Challenges have since been progressively taken up across European PVC value chains. The VinylPlus® programme uses an updated version of the five Challenges as a basis for voluntary commitments and transparent auditing of progress against published targets. Initial framing of the five TNS Sustainability Challenges for PVC were drafted consciously for generic relevance to other materials. Assessing the sustainability performance of some alternative materials to PVC against the five Sustainability Challenges reveals different sustainability performance in a range of potential applications. This highlights the danger inherent in automatic selection or deselection of materials in the absence of assessment of options on a ‘level playing field’ of sustainability principles. The five TNS Sustainability Challenges for PVC remain valid today and into the longer-term future as a basis for making stepwise, profitable progress towards the goal of sustainability for PVC and other materials

Thermal stresses in borehole heat exchangers

The backfilling materials of borehole heat exchangers (BHE), particularly the grout material, must provide a suitable thermal contact and ensure durability to the induced thermal stresses because of the heat loading. In this paper, the thermal stresses that occurred in BHEs because of heat injection or extraction is investigated with an analytical solution of a hollow cylinder model that is adapted for time-dependent heat loading, the geometry of a BHE, and the thermo-mechanical properties of surrounding ground conditions. Firstly, the hollow cylinder model is solved with the considered boundary conditions in 2D plane stress. Secondly, the temperature differences at the inner and outer circles of the cylinder are evaluated with the heat line source models for continuous and discontinuous loading to observe the impact of the heat loading schedule. The developed analytical solution for thermal stress investigation is validated with numerical models. It is demonstrated that the analytical solutions agree well with numerical results for two types of BHE configurations (co-axial and single U-shaped pipes). Furthermore, the calculated maximum stresses are compared with the tensile strength of grout materials obtained from Brazilian tests. It is predicted that the thermal contraction of the grout, partially constrained by the surrounding rock, generates tensile stresses that may lead to cracking in the BHE. According to the results, the stiffness of rock has a primary role on the developed tensile stresses, and the relationship between the thermal conductivity of the ground and of the grout induces a proportional impact on the magnitude of thermal stresses.SCOPUS: ar.jFLWINinfo:eu-repo/semantics/publishe

Selektive Hydroxylierung von Kohlenwasserstoffen mit Hilfe chemischer Verfahren am Beispiel der Herstellung von Phenol aus Benzol Abschlussbericht

Single-stage selective hydroxylation of aromatic hydrocarbons is one of the most interesting scientific challenges in oxidation catalysis. The hydroxylation of benzene into phenol is presented here as an example. It takes place both in the gaseous and liquid phase on heterogeneous V, Ti, or Cu catalysts on different catalyst carriers. Oxidants were hydrogen peroxide or oxygen in the presence of a reduction agent, e.g. hydrogen, iso-propanol or aldehydes. Oxidation of benzene into phenol with dinitrogen oxide in the liquid phase with benzene as solvent was carried out for the first time ever. In the presence of HZSM-5, a phenol selectivity of 95 percent was achieved with a benzene conversion of 1.8 percent. This method provided a patentable solution for phenol production.Die einstufige selektive Hydroxylierung aromatischer Kohlenwasserstoffe ist gegenwaertig eine der wissenschaftlich interessantesten Herausforderungen der Oxidationskatalyse. Am Beispiel der Hydroxylierung von Benzol zu Phenol werden im hier vorliegenden Vorhaben Beitraege zur Loesung dieses Problems geliefert. Die Hydroxylierung von Benzol erfolgte sowohl in der Gas- als auch in der Fluessigkphase an heterogenen vanadium-, titan- oder kupferhaltigen Katalysatoren auf unterschiedlichen Traegern. Als Oxidationsmittel wurden Wasserstoffperoxid oder Sauerstoff in Gegenwart eines Reduktionsmittels, wie z.B. Wasserstoff, iso-Propanol oder Aldehyde, verwendet. Erstmals konnte die Oxidation von Benzol zu Phenol mit Distickstoffoxid in der Fluessigphase (Benzol als Loesungsmittel) durchgefuehrt werden. In Gegenwart von HZSM-5 wurde bei einem Benzolumsatz von 1,8% eine Phenolselektivitaet von 95% erzielt. Mit dieser Verfahrensweise konnte ein patentfaehiger Loesungsweg fuer die Phenolherstellung erarbeitet werden. (orig.)SIGLEAvailable from TIB Hannover: F02B1565 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung, Berlin (Germany)DEGerman

Selektive Hydroxylierung von Kohlenwasserstoffen mit Hilfe biologischer Verfahren am Beispiel der Herstellung von Phenol aus Benzol Abschlussbericht

A biotechnological process for selective hydroxylation of aromatic compounds was to be developed. Phenol production was used as an example. It can be produced in principle either from benzene or from toluene. The first phase of the project focused on toluene, which is tolerated better by bacteria, and the reaction of toluene into benzoic acid produces just as many reduction equivalents as required for oxidation of benzoic acid to benzoic acid-cis-1,2-dihydrodiol. Two strains of bacteria were developed specially for this purpose. The first was the toluene-tolerant strain Pseudomonas putida Idaho (Cruden et al., 1992) in which the benzoic acid-cis-1,2-dihydrodiol dehydrogenase genes were inactivated. The second was a derivative of the strain Pseudomonas putida U-JT103 (Rossiter et al., 1987; Jenkins eta al., 1995; Morawski et al., 1997) which is known to be capable of converting benzoic acid into benzoic acid-cis-1,2-dihydrodiol just like Ralstonia eutropha B9. Although both bacterial strains were capable of converting toluene into benzoic acid-cis-1,2-dihydrodiol, it was not possible so far to produce stoichiometric amounts of benzoic acid-cis-1,2-dihydrodiol from toluene or its metabolites.Ziel des Forschungsvorhabens war es, ein biotechnologisches Verfahren zur selektiven Hydroxylierung von aromatischen Verbindungen am Beispiel der Herstellung von Phenol zu entwickeln. Wie in der Zielsetzung ausgefuehrt gibt es prinzipiell die Moeglichkeit Benzol oder Toluol als Ausgangsverbindungen einzusetzen. Aufgrund der Tatsache, dass (i) Toluol von Bakterien besser toleriert wird als Benzol und dass (ii) der Umsatz von Toluol zur Benzoesaeure genauso viele Reduktionsaequivalente liefert wie fuer die Oxidation von Benzoesaeure zu Benzoesaeure-cis-1,2-dihydrodiol notwendig sind, wurde im Laufe der ersten Phase des Projektes beschlossen, ein Verfahren ausgehend von Toluol zu entwickeln. Hierfuer war es notwendig Produktionsstaemme zu konstruieren, die in der Lage sind, Toluol zu Benzoesaeure-cis-1,2-dihydrodiol umzusetzen. Es gelang zwei solche Produktionsstaemme mittels molekularbiolgogischer Methoden zu erhalten. Bei dem einen Konstrukt handelt es sich um den Toluol tolerierenden Bakterienstamm Pseudomonas putida Idaho (Cruden et al., 1992), bei dem die Benzoesaeure-cis-1,2-dihydrodiol-Dehydrogenase/Gene inaktiviert wurden. Bei dem zweiten Konstrukt handelt es sich um eine Derivat des Bakterienstammens Pseudomonas putida U-JT103 (Rossiter et al., 1987; Jenkins et al., 1995; Morawski et al., 1997), von dem bekannt war, dass er, entsprechend wie Ralstonia eutropha B9, Benzoesaeure in Benzoesaeure-cis-1,2-dihydrodiol umwandeln kann. Auf diesen Stamm wurde ein Modul mit den benoetigten Genen der Toluoloxidation uebertragen. Obwohl fuer beide Staemme gezeigt werden konnte, dass sie Toluol zu Benzoesaeure-cis-1,2-dihydrodiol umsetzen koennen, ist es bislang nicht gelungen, Benzoesaeure-cis-1,2-dihydrodiol in stoechiometrischen Mengen aus Toluol oder dessen Metaboliten herzustellen. (orig.)SIGLEAvailable from TIB Hannover: F02B1566 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung, Berlin (Germany)DEGerman