HRTEM and Molecular Modeling of the MoS 2-Co9 S 8 Interface: Understanding the Promotion Effect in Bulk HDS Catalysts

As environmental regulations increase, more selective transition metal sulfide (TMS) catalytic materials for hydrotreating applications are needed. Highly active TMS catalysts become more and more desirable triggering new interest for unsupported Co-promoted MoS2-based systems that have high volumetric activity as reported here. Contrary to the common observation for alumina-supported MoS2-based catalysts, we found in our previous studies with dibenzothiophene (DBT) hydrodesulfurization (HDS) that the catalytic activity is directly proportional to the increase of surface area of the sulfide phases (Co9S8 and MoS2) present in Co-promoted MoS2 unsupported catalysts. This suggests that activity is directly connected with an increase of the contact surface area between the two sulfide phases. Understanding of the nature of the possible interaction between MoS2 and Co9S8 in unsupported catalytic systems is therefore critical in order to get a more generalized overview of the causes for synergy. This has been achieved herein through the detailed characterization by XRD, XPS, and HRTEM of the highly active Co9S8/MoS2 catalyst resulting in a proposed model for a Co9S8/MoS2 interface. This model was then subjected to a DFT analysis to determine a reasonable description of the surface contact region between the two bulk phases. Modelling of the interface shows the creation of open latent vacancy sites on Mo atoms interacting with Co and formation of direct Co-Mo bonds. Strong electron donation from Co to Mo also occurs through the intermediate sulfur atom bonded to both metals while an enhanced metallic character is also found. These changes in coordination and electronic properties are expected to favor a synergetic effect between Co and Mo at the proposed localized interface region between the two bulk MoS2 and Co9S8 phases.CONACYT, Mexico 207997MRTI of UTEP, Cotton Trust UTEPMicrolectronics Research Lab of UT-Austin and Departamento de Educacion y Cultura of Gobierno del Estado de ChihuahuaMicroelectronics Research Cente

Healthand well-being in urban areas : the WHO Healthy Cities project

The increasing number of people in the city takes the countries and organizations to ask themselves about the direction of urban areas in the provision of quality life and sustainability.The WHO promotes the Healthy Cities project to encourage local planning actions to provide more health and sustainability for cities.Viana do Castelo follows this directivedeveloping a monitoring system that allows reflection on the promotion of the well-being and health care of itscitizens

Urban observatories, tools for monitoring cities

The growth of urban areas, and all the problems that this fact entails, make more immediate the need to search for tools that are able to assist urban management. The urban observatories are, then, a tool that through indicators allows monitoring of the cities, assessing their progress over time. The observatories are also important to support decision making, involvement of people in decisions, data analysis and compilation and availability of data, which were previously unavailable to the general public. This paper makes a synthesis of the literature on the theme of Urban Observatories as a tool for monitoring our cities, with the objective to serve as a theoretical basis for the possible implementation of a project of this kind in Portugal

Observatórios urbanos, ferramentas para monitorização das cidades

O crescimento permanente das áreas urbanas e todos os problemas que esse facto acarreta, faz com que seja importante adotar ferramentas que consigam auxiliar a gestão urbana. Os observatórios urbanos são, então, uma ferramenta que, através de indicadores, permitem a monitorização das cidades, avaliando a sua evolução ao longo do tempo, e comparando-as com outras cidades. Os observatórios são ainda importantes no apoio à tomada de decisão, no envolvimento da população nas decisões, na análise de dados e compilação e disponibilização de relatórios, que antes não estavam disponíveis para o público em geral. Neste artigo é feita uma síntese bibliográfica sobre a temática dos Observatórios Urbanos como ferramentas para monitorização das cidades, tendo por objetivo servir de base teórica para a possível implementação de um projeto deste tipo em Portugal

Urban air dispersion model of a mid-sized city. Validation methodology

Viana do Castelo is a mid-sized city located on the northwest Portuguese seaside, which undertook the challenge of developing an environmental program leading to the integration in the Healthy Cities European Network. Within this program includes prediction of pollutant concentration for NO2, CO, PM10, O3 and C6H6. This paper presents the methodology developed to validate the modelled results. Predicted concentrations were compared against measured concentrations of a chosen pollutant: Carbon Monoxide, CO. The methodology adopted was based in BOOT statistical approach. Five comparison statistics were calculated for three test points in order to find out the quality of the modelled results. Additionally, a hourly profile of predicted versus measured concentrations was developed.(undefined

Validation study of urban air dispersion model of Viana do Castelo

The City of Viana do Castelo in Portugal has developed an air quality program, which includes prediction of pollutant concentration for NO2, CO, PM10, O3 and C6H6. A range of numerical models were used to produce the concentration maps: the ADMS-Urban model for the pollutants dispersion; the Hills model to calculate air flow and turbulence over complex terrain, including the effects of variable surface roughness; the CORINAIR v.5 to estimate traffic emissions. This paper presents the methodology developed to validate the modelled results. Predicted concentrations were compared against measured concentrations of a chosen pollutant: Carbon Monoxide, CO. Five comparison statistics were calculated for three test points in order to find out the quality of the modelled results. Additionally, a hourly profile of predicted versus measured concentrations was developed

A proposed methodology for understanding urban growth pattern : a case study in Siem Reap, Cambodia

In this paper, the main goal is to understand the relationship between urban growth and physical factors in order to determine the potential area for future urban expansion. A methodology is suggested for understanding urban growth pattern in Siem Reap which could effectively sustain archaeological sites and to balance the land use between urban and non-urban areas in Siem Reap, Cambodia. Remote sensing technique is used to analyze land use maps of Siem Reap from 1993 to 2011. Results show that urban-built up area increased significantly which causes the forest land to reduce steadily from 1993 to 2003 in the Siem Reap archaeological sites. In addition, Geographic Information System (GIS) is applied to analyze urban growth pattern. Geo-processing and logical functions are applied to detect and quantify the land use changes, especially urban changes. Two main factors are used to analyze the urban driving growth in Siem Reap, which are distance to road networks and population density. Pearson correlation statistics is applied to justify the relationship between the factors and urban area growth

Electric vehicle and conventional vehicle. Urban air pollution assessment

Road traffic is the main source of air pollutant emissions in urban areas. Pollutant emissions can be evaluated and calculated using mathematical models based on the characteristics of traffic flowing in roads. This article aims to assess the air pollution produced by a fleet of vehicles with conventional (diesel and petrol) and electrical (hybrid and electric) motorization, in the city centre of Braga. The scientific toolbox adopted to develop the studies includes emission models to estimate emission data and a GIS platform