Synthesis–Structure–Activity Relations in Fe-CHA for C–H Activation: Control of Al Distribution by Interzeolite Conversion

The search for structurally relevant Al-arrangements in zeolites is an important endeavor for single site catalysis. Little is known about the mechanisms and zeolite dynamics during synthesis that are responsible for creating those Al-ensembles. Here, new synthetic strategies for creating Al-hosts in small-pore zeolites suitable for divalent cation catalysis are uncovered, leading to a mechanistic proposal for Al-organization during crystallization. As such, unique synthesis-structure-activity relations are demonstrated for the partial oxidation of methane on Fe-exchanged CHA-zeolites. With modified interzeolite conversions, the divalent cation capacity of the resulting high Si SSZ-13 zeolites (Si/Al ~ 35) can be reproducibly controlled in a range between 0.04 and 0.34 Co²⁺/Al. This capacity is a proxy for the distribution of framework aluminum in pairs and correlates with the methanol production per Al when these zeolites host the α-Fe^(II) redox active site. The uncovered IZC synthesis-structure relations paint an Al-distribution hypothesis, where incongruent dissolution of the starting USY zeolite and fast synthesis kinetics with atypical growth modes allow assembling specific Al-arrangements, resulting in a high divalent cation capacity. Prolonged synthesis times and high temperatures overcome the energetic barriers for T-atom reshuffling favoring Al-isolation. These mechanisms and the relations uncovered in this work will guide the search for relevant Al-ensembles in a range of zeolite catalysts where controlling the environment for a single active site is crucial

Aplicació didàctica de la ràdio al context escolar

Aquest treball pretén explorar l’ensenyament i aprenentatge del valencià i en valencià des d’un punt de vista pragmàtic mitjançant una eina que permet dotar a l’escola d’activitats que propicien un aprenentatge significatiu: la ràdio. A través d’un projecte de ràdio escolar es donarà resposta a dos aspectes primordials: el disseny d’activitats que asseguren el desenvolupament de les capacitats dels alumnes mitjançant situacions de la vida quotidiana, i el fet de propiciar situacions comunicatives en valencià perquè els infants tinguen una millor competència comunicativa sense bandejar el folklore valencià, que incrementarà el sentiment de pertinença dels estudiants, sobretot dels castellanoparlants.This article is intended to explore the Valencian teaching and learning process from a pragmatic point of view, using the radio, a tool that provides the school with activities which facilitate a meaningful learning. For this purpose, the objective of the school radio project is to answer the following crucial aspects: the need to implement activities towards the development of the students’ skills, by means of everyday situations, and providing communicative situations in Valencian to develop their communicative competence. Nor is it overlooked that Valencian folklore must be facilitated and consequently, the students’ sense of belonging will foster, particularly among the Spanish speakers’ ones

Empirical Analysis of Impacts of Instance-Driven Changes in Ontologies

Abstract. Changes in the characterization of instances in digital content are one of the rationales to evolve ontologies that support a domain. These changes can have impacts on one or more of interrelated ontologies. Before implementing changes, their impact on the target ontology, other dependent ontologies or dependent systems should be analysed. We investigate three concerns for the determination of impacts of changes in ontologies: representation of changes to ensure minimum impact, impact determination and integrity determination. Key elements of our solution are the operationalization of changes to minimize impacts, a parameterization approach for the determination of impacts, a categorization scheme for identified impacts, and prioritization technique for change operations based on the severity of impacts