João P. Marques

Infrared spectroscopic study of the acid properties of dealuminated BEA zeolites

Abstract A series of HBEA samples were prepared by dealumination through three different methods (steaming, treatments with hydrochloric acid and ammonium hexafluorosilicate (HFS) solutions) of a parent sample with total and framework Si:Al ratios of 12.5 and 33, respectively, constituted of 20 nm crystallites. The samples were characterized by XRD, nitrogen adsorption and pyridine adsorption–desorption followed by IR spectroscopy. Whereas the three dealumination treatments have practically no effect on crystallinity and nitrogen adsorption properties, they cause large changes in the ranges of the O–H bond stretching modes (3300–3800 cm−1) and of the most intense IR absorption of pyridine (1400–1700 cm−1). Treatments with HCl or HFS cause the most significant changes: disappearance of the 3662 and 3782 cm−1 bands corresponding to extraframework Al species and to tricoordinated Al species partially connected to the framework, respectively, appearance of additional bands at 1603 and 1446 cm−1 ascribed to a new type of pyridine species coordinated to Lewis sites (PyL2) and for desorption temperatures above 350 °C, of a band at 1462 cm−1 generally ascribed to iminium ions, apparently at the expense of the PyL2 band. In agreement with this formation of iminium ions, desorption at high temperatures causes the complete disappearance of pyridinium ions without complete restoration of the acidic bridging hydroxyl band. PyL2 species are proposed to be pyridine molecules coordinated to Lewis sites and interacting through hydrogen bond with protonic sites.

A novel self-indicative vesicle based on a iron(II) complex

An iron(II) complex with a lipophilic derivative of 2,2′-bipyridine was synthesized and found to aggregate in aqueous solution, yielding vesicles with a mean diameter of 1000 nm; preliminary cyclic voltammetry experiments show that the complex forms redox-active films at the electrode surface.

A Bottom-Up Competency Modeling Approach

Competency-based management i.e. linking and assigning work according to the competencies required, has been acknowledged as a key enabler of organizational effectiveness and highlights the importance of modeling organizational competencies. Whereas Enterprise Architectures (EA) model organizations from different perspectives that describe and inter-relate their processes and resources, most EA frameworks provide limited means to model competencies. Available competency modeling approaches rely on static classification models that prove difficult to adjust to the constant changes in competency requirements. We propose a bottom-up modeling approach for representing organizational competencies using semantic units such as actions, goals and resources that (1) provides a more flexible competency classification framework, (2) allows answering questions about different competency-related concerns, and (3) allows assessing the alignment between the competencies required by activities and the competencies held by the actors performing them. This paper describes the competency model proposed and a set of tools used in supporting the model building process. Some benefits of the model are illustrated with a case study in an organizational setting.

Retrofit design of hydrogen distribution systems: a practical case study

Abstract The recent environmental restrictions to cut down pollutant gas emissions, along with the increasing drive to process heavy and sour crude oils, and the refining market trends toward gasoline and middle distillate fuels, have led to increased hydrogen demands associated with hydrotreating and hydrocracking processes. This manuscript addresses the synthesis of optimal hydrogen distribution systems bearing in mind both economic and operational issues. The optimal flowsheet configuration is established following a deterministic optimisation approach. One practical case study is provided to highlight the importance of an effective hydrogen management strategy amongst other production planning and scheduling decisions. This work was carried out within an industrial research project in close collaboration with Galp Energia and it is focused on a Petrogal’s refinery located near Sines, Portugal.

H2TT – A pinch analysis software tool for refinery hydrogen network management

Abstract Hydrogen management practices in the petroleum industry aim at maximising refining gross margins while addressing environmental and production planning issues. A novel pinch analysis software tool – H2TT – establishes targets for the minimum hydrogen utility consumption prior to detailed network design. H2TT is an interactive spreadsheet-based software programmed in Visual Basic for Applications that analyses the potential for reusing hydrogen across the refinery based on pinch analysis principles. This software identifies the existence of bottlenecks in the hydrogen distribution system and gives valuable insights into the appropriate placement of additional purification units within the hydrogen network. Moreover, it can be used to assess the availability of hydrogen at different purity levels. One example is provided to illustrate the applicability of H2TT for the integration hydrogen resources in refineries and petrochemical plants. This work was carried out within an industrial research project in close collaboration with Galp Energia and is focused on a Petrogal refinery located near Sines, Portugal.

IMPACT OF LEFT ATRIAL APPENDAGE PERCUTANEOUS OCCLUSION IN LEFT ATRIUM STRUCTURE AND FUNCTION: AN EXPERIMENTAL STUDY

Favorable results with percutaneous occlusion of the left atrial appendage (LAA) for the prevention of thromboembolic events in patients with non–valvular atrial fibrillation, has lead to a widespread use of this technique. Long–term effects on left atrial (LA) function are unclear and its