Synthesis and Characterization of Ni-WO3/Sulfated Zirconia Nano catalyst for Isomerization of N-Hexane and Iraqi Light Naphtha

This work deals with preparation of Sulfated Zirconia catalyst (SZ) for isomerization of n-hexane model and refinery light naphtha, as well as enhanced the role of promoters to get the target with the mild condition, stability, and to prevent formation of coke precursors on strong acidic sites of the catalyst. The prepared SZ catalysts were characterization by fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer –Emmett-Teller (BET) surface area analysis, Thermogravimetric Analysis (TGA), Scanning Electron Microscope (SEM) and atomic force microscopy (AFM) Analyzer. The results illustrate that the maximum conversion and selectivity for n-hexane isomerization with Ni-WSZ and operating temperature of 150 °C was 80.1% and 96 % respectively .Other set of experimental with light naphtha , the results show that the maximum conversion and selectivity with Ni-WSZ and operating temperature of 150 °C was 73.6% and 74% respectively.

Novozym® 435 and Lipozyme® RM IM as Biocatalysts for Benzyl Benzoate Synthesis

With the ever-increasing demand for clean technology in the industrial sector, natural methods, such as enzyme-catalyzed, represent a sustainable alternative to industrial chemical processes. In this context, the synthesis of benzyl benzoate ester using commercial immobilized lipases was evaluated. For this, a kinetic study was carried out to determine the reaction time (24 h) and enzyme concentration (10 wt%). Then, a 22 full factorial design was proposed to evaluate the effect of molar ratio (benzyl alcohol to benzoic anhydride) and temperature on conversion of benzyl benzoate in the presence of tert-butanol as solvent. For the Novozym® 435, maximum conversion (32%) was achieved at 60 ºC, using a molar ratio of 1:5 (alcohol to anhydride). A maximum conversion of 51% was obtained for Lipozyme® RM IM at 40 ºC and the molar ratio of 1:5. The benzyl benzoate showed moderate antimicrobial action against S. aureus (MIC = 0.05 mg μL-1). With the results, the conclusion was that the methodology of design of experiments was adequate for the proposed system and allowed the optimization of the production of benzyl benzoate.

Valorization of Restaurant Waste Oil Over Cow-bone Doped Siliceous Termite Hills Catalysts Towards Biodiesel Production

Treated termite hill is a potent heterogeneous catalyst in the synthesis of biodiesel from restaurant waste oil (RWO). Two catalysts (raw cow-bone supported on silica; R-SC1.5 and calcined cow bone supported on silica; K-SC1.5) were developed and used in biodiesel production. The maximum conversion of RWO was 95.12 % using K-SC1.5 at reaction time 2.5 h, methanol to oil ratio 9:1, temperature 65°C and catalyst loading of 2 %w/w. The prepared catalysts were characterized using SEM, EDAX, FTIR, XRD and BET analysis. The kinetics of the RWO with R-SC1.5 and K-SC1.5 was further studied. The Ea and A were found to be 41.4 kJ mol− 1, 53.41 kJ mol− 1 and 2.24 ×104 min− 1, 2.29×106 min− 1 respectively. The transesterification reaction adhered to first order law, while physicochemical properties were within ASTM limits. Reusability of K-SC1.5 was also examined, which revealed effectiveness up to 5 reuses without significant reduction in biodiesel yield.

β-Glucosidase and β-Galactosidase-Mediated Transglycosylation of Steviol Glycosides Utilizing Industrial Byproducts

Stevia rebaudiana Bertoni is a plant cultivated worldwide due to its use as a sweetener. The sweet taste of stevia is attributed to its numerous steviol glycosides, however, their use is still limited, due to their bitter aftertaste. The transglycosylation of steviol glycosides, aiming at the improvement of their taste, has been reported for many enzymes, however, glycosyl hydrolases are not extensively studied in this respect. In the present study, a β-glucosidase, MtBgl3a, and a β-galactosidase, TtbGal1, have been applied in the transglycosylation of two steviol glycosides, stevioside and rebaudioside A. The maximum conversion yields were 34.6 and 33.1% for stevioside, while 25.6 and 37.6% were obtained for rebaudioside A conversion by MtBgl3a and TtbGal1, respectively. Low-cost industrial byproducts were employed as sugar donors, such as cellulose hydrolyzate and acid whey for TtbGal1- and MtBgl3a- mediated bioconversion, respectively. LC-HRMS analysis identified the formation of mono- and di- glycosylated products from stevioside and rebaudioside A. Overall, the results of the present work indicate that both biocatalysts can be exploited for the design of a cost-effective process for the modification of steviol glycosides.

IMPATT Diodes Based on GaAs for Millimeter Wave Applications with Reference to Si

The small signal characteristics of DDR IMPATTs based on GaAs designed to operate at mm-wave window frequencies such as 94, 140, and 220 GHz are presented in this chapter. Both the DC and Small signal performance of the above-mentioned devices are investigated by using a small signal simulation technique developed by the authors. The efficiency, output power and power density of GaAs IMPATT is higher than that of Si IMPATT. Results show that the DDR IMPATTs based on GaAs are most suitable for generation of RF power with maximum conversion efficiency up to 220 GHz. The noise behavior of GaAs IMPATT yield less noise as compared to Si IMPATT.

Highly efficient oxidative cleavage of olefins with O2 under catalyst-, initiator- and additive-free conditions

Described are the first example of 1,4-dioxane-promoted oxidative cleavage of olefins to carbonyls with atmospheric oxygen as the sole oxidant and the maximum conversion was obtained up to 95%. This...

On the use of catalysis to bias reaction pathways in out-of-equilibrium systems

We show, via simulations, how catalytic control over individual paths in a fuel-driven non-equilibrium chemical reaction network in batch or flow gives rise to responses in maximum conversion, lifetime and steady states.

Design and Analysis of Combustion Chamber for HAN Based Mono Propulsion System Thruster for Spacecraft Application

This paper presents a preliminary dimensional study of combustion chamber using Hydroxyl Ammonium Nitrate (HAN) propellants for spacecraft application. The combustion chamber consists of two parts namely thrust chamber and Convergent-Divergent (C-D) nozzle. The design for combustion chamber is very much important because the chemical energy in the propellant released within this closed volume i.e., thrust chamber and gets expanded through the C-D nozzle part. So the chamber must be designed to provide a necessary space for the propellants to react and release maximum available energy and also it should prevent the loss of energy in the form of heat. The C-D nozzle should be optimally designed to allow the maximum conversion of enthalpy into kinetic energy. So, the thrust chamber and C-D nozzle are designed in an optimum size for releasing the heat to convert maximum available heat energy from the combustion of HAN propellant into exhaust velocity for HAN based monopropellant thruster. In this work the combustion chamber i.e. thrust chamber and C-D nozzle are designed at 16 bar pressure to generate a thrust of 11 N. CFD analysis is done to show the pressure and temperature variation in the combustion chamber modeled for 11 N thrust and chamber pressure of 16 bar for spacecraft application. From the analysis result it is found that monopropellant engine with the propellant combination of HAN+ Methanol+ Ammonium Nitrate + Water is suitable for design of Attitude & Orbit Control System (AOCS) thrusters.

Simulating Trambouze reaction for a series reactor

Simulating the existing data on Trambouze reaction is compiled in this article. The objective of the work is to present the change of volumetric flow rate and the inlet concentration of key reactant A in a series continuous stirred tank reactor-plug flow reactor (CSTR-PFR) configurations. The volumetric flow rate does not affect selectivity and conversion for a constant volumetric flow rate operating condition, entering CSTR and PFR, at a specific concentration of reactant. The CSTR-PFR series reactor configuration is proposed for the aim of maximizing the selectivity of the desired product B in comparison to the undesired products X and Y. CSTR as the first reactor is capable to achieve the maximum conversion at the highest selectivity of A. PFR is then proposed after CSTR in a configuration of CSTR-PFR, to allow higher conversion value to be achieved for the resulted outlet stream conditions coming out of the first reactor, CSTR. Both reactors commonly encounter a decrease in the initial concentration of A and an increase to the formation of other products. The CSTR entering volumetric flow rate influence the volume sizes needed in achieving the maximum selectivity and conversion

Synergistic biodegradation of aromatic-aliphatic copolyester plastic by a marine microbial consortium

The degradation of synthetic polymers by marine microorganisms is not as well understood as the degradation of plastics in soil and compost. Here, we use metagenomics, metatranscriptomics and metaproteomics to study the biodegradation of an aromatic-aliphatic copolyester blend by a marine microbial enrichment culture. The culture can use the plastic film as the sole carbon source, reaching maximum conversion to CO2 and biomass in around 15 days. The consortium degrades the polymer synergistically, with different degradation steps being performed by different community members. We identify six putative PETase-like enzymes and four putative MHETase-like enzymes, with the potential to degrade aliphatic-aromatic polymers and their degradation products, respectively. Our results show that, although there are multiple genes and organisms with the potential to perform each degradation step, only a few are active during biodegradation.