scholarly journals Zeolites for Fine Chemical Production State of Art and Perspectives

2017 ◽  
Vol 3 (4) ◽  
pp. 231 ◽  
Author(s):  
Mario G. Clerici
Keyword(s):  
Sustainable Development ◽  
Vegetable Oils ◽  
Renewable Resources ◽  
Active Sites ◽  
Zeolite Catalysts ◽  
Chemical Production ◽  
Fine Chemical ◽  
Acid Catalysed Reactions ◽  
State Of Art

The paper analyses the role of catalysis and that of renewable resources in the frame of a sustainable development. The possible uses of natural feedstocks for chemical production and the application of catalytic<br />methods to their transformations are reviewed, with emphasis on carbohydrates and vegetable oils and on zeolite catalysts, respectively. The problems arising from the embedment of active sites on the catalyst<br />surface are discussed, with the aid of specific examples taken from oxidation and acid catalysed reactions.

scholarly journals Identification of the Mechanism of NO Reduction with Ammonia (SCR) on Zeolite Catalysts

2020 ◽  
Author(s):  
Konstantin Khivantsev ◽  
Ja-Hun Kwak ◽  
Nicholas R. Jaegers ◽  
Miroslaw A. Derewinski ◽  
János Szanyi
Keyword(s):  
Active Sites ◽  
No Reduction ◽  
Catalytic Reduction ◽  
Molecular Nitrogen ◽  
Acid Sites ◽  
Zeolite Catalysts ◽  
Catalytic Cycle ◽  
Rate Limiting Step ◽  
Catalytically Active

<p>Cu/Zeolites catalyze selective catalytic reduction of nitric oxide with ammonia. Although the progress has been made in understanding the rate-limiting step of reaction which is reoxidation of Cu(I)(NH<sub>3</sub>)<sub>2</sub> with oxygen to restore the catalytically active Cu(II) site, the exact NO reduction chemistry remained unknown. Herein, we show that nitrosyl ions NO<sup>+</sup> in the zeolitic micropores are the true active sites for NO reduction. They react with ammonia even at below/room temperature producing molecular nitrogen through the intermediacy of N<sub>2</sub>H<sup>+</sup> cation. Isotopic experiments confirm our findings. No copper is needed for this reaction to occur. However, when NO<sup>+</sup> reacts, “freed up” Bronsted acid site gets occupied by NH<sub>3</sub> to form NH<sub>4</sub><sup>+</sup> – and so the catalytic cycle stops because NO<sup>+</sup> does not form on NH<sub>4</sub>-Zeolites due to their acid sites being already occupied. Therefore, the role of Cu(II) in Cu/Zeolite catalysts is to produce NO<sup>+</sup> by the reaction: Cu(II) + NO à Cu(I) + NO<sup>+ </sup>which we further confirm spectroscopically. The NO<sup>+</sup> then reacts with ammonia to produce nitrogen and water. Furthermore, when Cu(I) gets re-oxidized the catalytic cycle then can continue. Thus, our findings are critical for understanding complete SCR mechanism.</p>

scholarly journals Application of vegetable oil-based biopolyols in manufacturing of rigid polyurethane foams – short review

2018 ◽  
Vol 1 (2) ◽  
Author(s):  
Aleksander Hejna
Keyword(s):  
Sustainable Development ◽  
Vegetable Oil ◽  
Vegetable Oils ◽  
Renewable Resources ◽  
Short Review ◽  
Paper Analysis ◽  
Polyurethane Foams ◽  
Rigid Polyurethane Foams ◽  
The Future

The development of polyurethane foams’ market, as well as ongoing trends associated with sustainable development cause increasingly growing interest in the utilization of materials from renewable resources. Great example of such phenomenon is the use of vegetable oils in manufacturing of foamed polyurethanes. These materials can be applied directly or after previous modifications in production of biopolyols, main constituents of polyurethanes. In this paper, analysis of polyurethane foams’ market was presented and forecasts pointing to the potentially increasing position of so-called bio-polyurethanes in the future. Moreover, this paper summarizes previously published reports related to the manufacturing of vegetable oil-based biopolyols and their further incorporation into formulations of rigid polyurethane foams.

scholarly journals Identification of the Mechanism of NO Reduction with Ammonia (SCR) on Zeolite Catalysts

2020 ◽  
Author(s):  
Konstantin Khivantsev ◽  
Ja-Hun Kwak ◽  
Nicholas R. Jaegers ◽  
Miroslaw A. Derewinski ◽  
János Szanyi
Keyword(s):  
Active Sites ◽  
No Reduction ◽  
Catalytic Reduction ◽  
Molecular Nitrogen ◽  
Acid Sites ◽  
Zeolite Catalysts ◽  
Catalytic Cycle ◽  
Rate Limiting Step ◽  
Catalytically Active

<p>Cu/Zeolites catalyze selective catalytic reduction of nitric oxide with ammonia. Although the progress has been made in understanding the rate-limiting step of reaction which is reoxidation of Cu(I)(NH<sub>3</sub>)<sub>2</sub> with oxygen to restore the catalytically active Cu(II) site, the exact NO reduction chemistry remained unknown. Herein, we show that nitrosyl ions NO<sup>+</sup> in the zeolitic micropores are the true active sites for NO reduction. They react with ammonia even at below/room temperature producing molecular nitrogen through the intermediacy of N<sub>2</sub>H<sup>+</sup> cation. Isotopic experiments confirm our findings. No copper is needed for this reaction to occur. However, when NO<sup>+</sup> reacts, “freed up” Bronsted acid site gets occupied by NH<sub>3</sub> to form NH<sub>4</sub><sup>+</sup> – and so the catalytic cycle stops because NO<sup>+</sup> does not form on NH<sub>4</sub>-Zeolites due to their acid sites being already occupied. Therefore, the role of Cu(II) in Cu/Zeolite catalysts is to produce NO<sup>+</sup> by the reaction: Cu(II) + NO à Cu(I) + NO<sup>+ </sup>which we further confirm spectroscopically. The NO<sup>+</sup> then reacts with ammonia to produce nitrogen and water. Furthermore, when Cu(I) gets re-oxidized the catalytic cycle then can continue. Thus, our findings are critical for understanding complete SCR mechanism.</p>

scholarly journals Social Acceptance of Forest-Based Bioeconomy—Swedish Consumers’ Perspectives on a Low Carbon Transition

2021 ◽  
Vol 13 (14) ◽  
pp. 7628
Author(s):  
Emil Nagy ◽  
Carolina Berg Rustas ◽  
Cecilia Mark-Herbert
Keyword(s):  
Sustainable Development ◽  
Renewable Resources ◽  
Path Dependence ◽  
Social Acceptance ◽  
Forest Biomass ◽  
Low Carbon ◽  
Consumer Awareness ◽  
Future Studies ◽  
Production And Consumption

The concept of the bioeconomy is associated with sustainable development changes and involves transitions in both production and consumption within systems. Many of these transitions relate to using renewable resources, like forest biomass, to meet basic needs, such as food, energy and housing. However, consumers must become aware of the forest-based bioeconomy so that they can contribute to the transition. This study aims to contribute to an understanding of this matter that may lead to social acceptance of the forest-based bioeconomy and, in particular, to Swedish consumer awareness of the concept and of a particular product (wooden multi-story buildings) representing the forest-based bioeconomy. The results show consumer awareness of forest sequestration capacity but less awareness of the connection to the forest-based bioeconomy and the role of wooden multi-story buildings. The results indicate a slow transition that is hindered by path dependence and limited comprehension among consumers of the effects of their choices for a forest-based bioeconomy. This study provides valuable insights for future studies of how consumer awareness and social acceptance of the forest-based bioeconomy are interconnected.

Utilization of renewable resources: Investigation on role of active sites in zeolite catalyst for transformation of furfuryl alcohol into alkyl levulinate

2021 ◽  
Vol 502 ◽  
pp. 111361
Author(s):  
B.J. Vaishnavi ◽  
S. Sujith ◽  
Nagendra Kulal ◽  
Pandian Manjunathan ◽  
Ganapati V. Shanbhag
Keyword(s):  
Renewable Resources ◽  
Furfuryl Alcohol ◽  
Active Sites ◽  
Zeolite Catalyst ◽  
Alkyl Levulinate

Modelling of catalysts and its relation to experimental problems

1992 ◽  
Vol 341 (1661) ◽  
pp. 255-268 ◽  
Keyword(s):  
Small Molecules ◽  
Active Sites ◽  
Thermal Activation ◽  
Porous Metal ◽  
Acid Sites ◽  
Zeolite Catalysts ◽  
Before And After ◽  
Porous Metal Oxides ◽  
And Diffusion

We illustrate the role of both computer simulation and the evaluation of electronic structure in the study of solid heterogeneous catalysis by reference to recent work in this laboratory on ( a ) microporous materials (that have a spatially uniform distribution of accessible active sites) and ( b ) non-porous metal oxides. Computational methodologies may be used to model, first, the structure of the uniform catalysts both before and after thermal activation, second, the docking and diffusion of molecules in solids and on their surfaces; and, third, the reaction pathways of molecules at the active site. We highlight recent successes in modelling (i) the structures of zeolitic solids, (ii) the sorption of hydrocarbons within them, (iii) the protonation of small molecules at the Bronsted acid sites in uniform solid acid (zeolite) catalysts, and (iv) the reactions of small molecules on CeO 2 and MgO surfaces.

The Role of Customary Law in Sustainable Development

2006 ◽  
Author(s):  
Peter Orebech ◽  
Fred Bosselman ◽  
Jes Bjarup ◽  
David Callies ◽  
Martin Chanock ◽  
...  
Keyword(s):  
Sustainable Development ◽  
Customary Law

Role of Teachers in Building the Concept of Sustainable Development: Success or Failure

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Ayaz Muhammad Khan ◽  
Amber Jamshaid ◽  
Tayyibah Roohi ◽  
Amna Ramzan
Keyword(s):  
Sustainable Development ◽  
Primary School ◽  
Sampling Technique ◽  
School Teachers ◽  
Primary School Teachers ◽  
Primary Level ◽  
Significant Difference ◽  
Role Of Teachers ◽  
Major Factors

Sustainable Development (SD) is a rich, challenging and thought-provoking construct in social sciences. The main purpose of this paper was to identify and explore the role played by primary school teachers in building up the idea of sustainable development (SD) among students. This paper was intended to identify that how a teacher can successfully execute the concept of SD by influencing students’ minds at the primary level. Quantitative survey technique were utilized for data collection. All the primary school teachers of Lahore division comprised the population of the study. Through multistage sampling technique, 352 primary school teachers were selected as participants of the study. A self-developed SD questionnaire incorporating four major factors (teachers’ awareness, pedagogy, curricular and co-curricular activities) with Cronbach’s alpha value = .93 was used to measure the role of teachers in building the sustainability concept among students at primary level. The results indicated a significant mean score difference among SD scores of teachers, sector wise (private and public). Furthermore, the results also reconnoitered the significant difference (p=.04) between the mean scores of female and male teachers in building up the SD concept in students’ minds.

The role of parliament in the sustainable development of the country: Agenda for Kazakhstan

2020 ◽  
pp. 29-52
Author(s):  
Aliya Kassymbek ◽  
Lazzat Zhazylbek ◽  
Zhanel Sailibayeva ◽  
Kairatbek Shadiyev ◽  
Yermek Buribayev
Keyword(s):  
Sustainable Development ◽  
The Sustainable Development
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