Propane Dehydrogenation over a Commercial Pt-Sn/Al2O3 Catalyst for Isobutane Dehydrogenation: Optimization of Reaction Conditions

The applicability of a commercial Pt-Sn/Al₂O₃ isobutane dehydrogenation catalyst in dehydrogenation of propane was studied. Catalyst performance tests were carried out in a fixed-bed quartz reactor under different operating conditions. Generally, as the factors improving propane conversion decrease the propylene selectivity, the optimal operating condition to maximize propylene yield is expected. The optimal condition was obtained by the experimental design method. The investigated parameters were temperature, hydrogen/hydrocarbon (H₂/HC) ratio and space velocity, being changed in three levels. Constrains such as the susceptibility of the catalyst components to sintering or phase transformation were also taken into account. Activity, selectivity and stability of the catalyst were considered as the measured response factors, while the space-time-yield (STY) was considered as the variable to be optimized due to its commercial interest. A STY of 16 mol·kg^-1·h^-1 was achieved under the optimal conditions of T 620℃, H₂/HC 0.6 and, weight hourly space velocity (WHSV) 2.2 h^-1. Single carbon-carbon bond rupture was found to be the main route for the formation of lower hydrocarbon byproducts.     

Carbon dioxide sequestration in petrochemical industries with the aim of reduction in greenhouse gas emissions

The mitigation of greenhouse gas emissions to acceptable levels is arguably the greatest environmental challenge these days. Vast utilization of fossil fuels and forest destruction are main causes of CO₂ increase in the atmosphere. Carbon dioxide sequestration that consists of separation, transportation and utilization or storage of CO₂, is one way for reduction of its emission, in which the most costly section is separation. Different methods can be used for carbon dioxide separation such as absorption, membrane separation, adsorption and cryogenic distillation. Economic, technical and environmental issues should be considered in selection of the technology for particular application. Carbon dioxide concentration, temperature, pressure and flow rate are influential operating parameters in the selection of the appropriate separation method. Nowadays, absorption is the worldwide industrial separation method. New researches are focused on developing new stable solvents and efficient column configuration with suitable internals to minimize pressure drop. Membrane separation and adsorption (PSA type) are other long-term alternatives that can increase separation efficiency and decrease separation cost. The level of energy consumption in various separation methods are in the order: chemical absorption>physical absorption>membrane separation. Because of high investment costs, current separation technologies are suitable for large concentrated sources. In the present paper, different processes for carbon dioxide separation are investigated and compared. Available technologies and commercial plants for CO₂ sequestration are provided.     

Organic food processing: a framework for concept,starting definitions and evaluation

In 2007 EU Regulation (EC) 834/2007 introduced principles and criteria for organic food processing. These regulations have been analysed and discussed in several scientific publications and research project reports. Recently, organic food quality was described by principles, aspects and criteria. These principles from organic agriculture were verified and adapted for organic food processing. Different levels for evaluation were suggested. In another document, underlying paradigms and consumer perception of organic food were reviewed against functional food, resulting in identifying integral product identity as the underlying paradigm and a holistic quality view connected to naturalness as consumers' perception of organic food quality. In a European study, the quality concept was applied to the organic food chain, resulting in a problem, namely that clear principles and related criteria were missing to evaluate processing methods. Therefore the goal of this paper is to describe and discuss the topic of organic food processing to make it operational. A conceptual background for organic food processing is given by verifying the underlying paradigms and principles of organic farming and organic food as well as on organic processing. The proposed definition connects organic processing to related systems such as minimal, sustainable and careful, gentle processing, and describes clear principles and related criteria. Based on food examples, such as milk with different heat treatments, the concept and definitions were verified. Organic processing can be defined by clear paradigms and principles and evaluated according criteria from a multidimensional approach. Further work has to be done on developing indicators and parameters for assessment of organic food quality. © 2013 Society of Chemical Industry     

A fast variable neighborhood search for p-hub median problem using social network analysis concepts

This study will contribute to the uncapacitated single allocation p-hub median problem (USApHMP) which is known as an NP-hard problem in the literature. This problem is concerned with locating of hub facilities in a network and allocating of each non-hub node to just one hub in order to minimize total transportation costs in the network. A hybrid variable neighborhood search (VNS) algorithm is proposed considering three structures of local search which are used as a combination of nested VNS and sequential VNS in the algorithm. For reduction of the dimensions in the nested part, social network analysis centrality measures for the node are used to choose elite points instead of all existing points in the local search structures. The obtained results demonstrate that this will not only retain quality of the solutions, but also reduce run time of the algorithm significantly. Three standard data sets (AP, CAB, and URAND) were used for numerical analysis. Computational results show that quality of the obtained solutions is good and able to compete with other heuristics addressed in the literature. From the viewpoint of execution time, it considerably outperforms all other algorithms. The intelligent search embedded in this algorithm makes it robust and efficient on networks with up to 400 nodes.     

VeriVANca framework: verification of VANETs by property-based message passing of actors in Rebeca with inheritance

International Journal on Software Tools for Technology Transfer - Vehicular ad hoc networks have attracted the attention of many researchers during the last years due to the emergence of autonomous...     

Applicability of sheep and pig models for cancellous bone in human vertebral bodies

The mineral content of cancellous bone from sheep and pig vertebral bodies was determined by ashing at 800 degrees C. The results were compared with published results for human vertebral cancellous bone. The results for sheep (0.37 +/- 0.06 gcm(-3), mean +/- standard deviation) were not significantly different (p = 0.127) to those from pigs (0.33 +/- 0.03 gcm(-3)). The results from both species were significantly higher (p < 0.001) than those from human bones (0.15 +/- 0.02 gcm(-3)). This means that cancellous bone from sheep and pig vertebral bodies is not a good model for corresponding human bone. However, sheep and pig bone are useful, for example, for providing stringent tests of cutting instruments to be used in human spinal surgery.     

Rheological and physical characterization of pressure sensitive adhesives from bio‐derived block copolymers

Over the past decade, the development of various monomers and polymeric materials from renewable natural resources has received increasing attention. Soybean oil, as one of the most abundant vegetable oils, has been widely used in recent studies. To enhance the reactivity of pure soybean oil, it can undergo through different processes such as acrylation and epoxidation. In this article, we investigated the viability of polymerized acrylated epoxidized soybean oil (PAESO) in the composition of pressure sensitive adhesives (PSAs). We studied the physical and rheological properties of PSAs composed of poly(styrene‐b‐AESO), and five different tackifiers and three plasticizers. To verify the compatibility of the tackifiers with the biopolymer, a library of 15 PSAs was prepared through solvent blending method and tested by differential scanning calorimetry. The viable formulations were then prepared through hot‐melt blending and characterized using 180° peel tester, and advanced rheometric expansion system. Results showed that the combination of an ester of hydrogenated rosin and a high solvating plasticizer with the synthesized biopolymer indicated best performance relative to other formulations. The comparison of this candidate with its petroleum‐based counterpart containing SIS demonstrates promising potential of the material to perform as well as commercialized PSAs. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46618.     

Oxidative Stability of Rice Bran Wax Oleogels and an Oleogel Cream Cheese Product

Recently, a number of publications demonstrated the successful applications of oleogels (OG) (liquid oils gelled through organogelators) in food products. Although many highlighted the health benefits of OG, potential negative impacts of thermal processing during oleogelation on nutrition and flavor quality of the OG‐based food are not fully studied. Hence, in this study, an oleogel‐cream‐cheese (OCC) product was formulated and the effects of OG processing on the oil's oxidative stability and the tocopherol content were investigated. The OG system used in the cheese product was prepared with high‐oleic soybean oil (HOSO) and rice bran wax. An ungelled cream‐cheese sample (UGCC) and two commercial cream‐cheese products were used as controls. Although high‐performance liquid chromatography data analysis showed a lower total tocopherol content in OG samples compared to HOSO, the samples’ α‐tocopherol content remained comparable. No significant differences were observed between the total tocopherol contents of OCC and UGCC cheese products, and the amount of all three‐tocopherol isomers remained constant during 14 days of storage. Although oxidation analysis showed more volatile compounds in OG samples compared to HOSO, there was only a minor difference in the volatile content between the OCC and UGCC samples. The results show minimal degradation of vegetable OG due to the thermal processing and storage that may help their potential application in dairy products.