The methanol-to-dimethyl ether (MTD) process has been considered one of the potential methods for manufacturing environmentally friendly fuel, i.e., dimethyl ether (DME). The process requires an efficient, stable, and sustainable catalyst. Herein, metal-organic frameworks (MOF-5, zinc-terephthalate framework) and ZIF-8 (zeolitic imidazolate framework, zinc-imidazolate) were used as sacrificial precursors for the fabrication of MOF-derived ZnO-doped carbon (ZnO@C) via a single carbonization step. The materials were characterized using X-ray diffraction (XRD), thermal analysis (thermogravimetric analysis (TGA) and differential thermal analysis (DTA)), X-ray photoelectron spectroscopy (XPS), Fourier transforms infrared (FT-IR), and nitrogen adsorption-desorption isotherms. The material's acidity was evaluated using isopropyl alcohol dehydration, chemisorption, and pyridine-temperature programming desorption (TPD) analysis. Data analysis reveals that the acidity of ZnO@C is due to Brønsted acidic sites of weak and intermediate strength. ZnO@C catalysts showed an excellent catalytic conversion (100%) towards DME via methanol dehydration with a selectivity of 100%. They displayed a high conversion and selectivity, increasing the percentage of methanol in the reacting stream and gas hourly space velocity (GHSV). They can be recycled several times with high catalytic activity and long-term stability for 160 h.
Conversion of methanol to dimethyl ether (MTD) has known to be one of the main routes for the production of a clean bio-fuel, i.e., dimethyl ether (DME). However, efficient, selective, and stable catalyst is highly required for production of DME especially at relatively low temperature. Herein, aluminum phosphate nanocatalysts were fabricated by a co-precipitation method in the presence of triethylamine (TEA) as a surfactant. Thermal, structural, spectroscopic, morphological and texture properties of the catalysts were characterized by thermal analyses (TG–DTA), X-Ray diffraction (XRD), Fourier transform infrared (FTIR), high resolution transmission electron microscopy (HR-TEM) and N2-sorption analyses. In addition, the acidity of these catalysts was evaluated by isopropyl alcohol dehydration and chemisorption of basic probes. Results of acidity and pyridine-TPD indicated that these catalysts possessed Brϕnsted acidic sites of weak and intermediate strengths. The results of catalytic activity demonstrated that aluminum phosphate nanocatalyst (AP1T1) calcined at 400 °C exhibited the best catalytic performance for methanol dehydration into DME with a conversion of 100% and a 100% selectivity at 250 °C. In addition, this catalyst (AP1T1) exhibits a unique behavior where its catalytic performance only decreases by 10% upon increasing the % of methanol in the reacting feed to 35%. Moreover, it possessed excellent long-term stability with almost the same efficiency after a period of 120 h. The observable catalytic activity of these catalysts was well linked to the catalyst acidity and the activation energy.
In this study, natural bentonite has been used as a highly efficient, and low-cost sorbent for the adsorptive removal of methylene blue (MB), crystal violet (CV), and fuchsine basic (FB) dyes from aqueous solutions. X-ray fluorescence (XRF), Thermogravimetry and differential thermal analyses (TG-DTA), X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) analyses for bentonite clay were performed. Results revealed that bentonite is an excellent sorbent for the elimination of these dyes with maximum adsorption capacities of 598.8, 929.7 and 875.2 mg g−1 for MB, CV, and FB, respectively. In addition, thermodynamic results reflected that the adsorption process is a spontaneous, endothermic, and of chemisorption nature. While kinetic studies specified that the adsorption of these dyes is ruled by the film diffusion and pore diffusion mechanism. Moreover, simultaneous removal of these dyes from their binary and ternary mixtures was also examined. A Regeneration study demonstrated that, bentonite can be recycled several times with almost the same efficiency.
The subject of the paper is the description of the category as objects L-fuzzifying soft preproximity spaces with structure preserving morphisms. We investigate the functorial relations between L-fuzzifying soft preproximity spaces and L-fuzzifying soft topological spaces. @ 2018 Academic Publications, Ltd.
In this paper, we introduce the concepts of (L;M)-fuzzy soft quasi-coincident neighborhood spaces and study their properties, where L be a completely distributive lattice with 0 and 1 elements and M be a strictly two-sided, commutative quantile lattice. Also, the relationships between these concepts were investigated. Furthermore, a characterization of LFS-continuous and LSN-mappings were given. @2017 Sayed, Elsanousy, Raghp and Kim.
Introducing the notions of soft t-sets, soft t*-sets, soft B-sets, soft α*-sets and
soft C-sets in the setting of soft topological spaces, we study some of its properties and investigate the relationships between them besides considering some variants of continuous maps on soft topological spaces.
©2017 African Mathematical Union and Springer-Verlag Berlin Heidelberg
In this paper, the concepts of (L;M)-fuzzy soft topological spaces, (L;M)-fuzzy soft base and (L; M)-fuzzy soft filter spaces were introduced and their properties were studied, where L be a completely distributive lattice with 0 and 1 elements and M be a strictly two-sided, commutative quantile lattice. Also, the relationships between these concepts were investigated.
@2017 Sayed, Elsanousy, Raghp and Kim.
Coronary artery disease affects millions of people all over the world including a major portion in Egypt every year. Although much progress has been done in
medical science, early detection of this disease is still a challenge for prevention. In this paper we, will extend the concept of fuzzy soft set theory so as to develop a
knowledge-based system in medicine and devise a prediction system named fuzzy soft expert system consisting of four main components. These are a fuzzification which translates inputs into fuzzy values, fuzzification of data sets to obtain fuzzy soft sets, a new fuzzy soft set by normal parameter reduction of fuzzy soft set and an algorithm to produce the resultant output. The fuzzy soft expert system developed is then used to predict for coronary artery disease using systolic blood pressure, low-density lipoprotein cholesterol, maximum heart rate, blood sugar, old peak and age of patients. A preliminary study is conducted on nine male patients undergoing treatment in the Cardiac Unit of the Faculty of Medicine, Assiut University, Egypt. It is found that the fuzzy soft expert system developed is able is to help the expert doctor to decide whether a patient needs to be given drug therapy or intervention.
@2016 Taiwan Fuzzy Systems Association and Springer-Verlag Berlin Heidelberg.
In this paper, some characterizations of fuzzifying β -compactness are given, including characterizations in terms of nets and β -subbases. Several characterizations of locally β -compactness in the framework of fuzzifying topology are introduced and the mapping theorems are obtained.
@ 2015 – IOS Press and the authors.
