MODELING THE EFFECT OF TEMPERATURE-INDUCED SURFACE-TENSION GRADIENT IN COATING PROCESSES

In the application of fluorescent lamp coating, clip marks formed during drying can adversely affect product quality, resulting in higher production cost and/or lower customer satisfaction. It is believed that these defects are caused by gradient in coating surface tension but their mechanisms are still not well understood. To facilitate a more systematic approach to coatings design, it is important to have a better understanding of the roles of surface tension in defect formation. A onedimensional mathematical model, which describes the tlow of drying coating on horizontal planar substrates, was developed in this study to investigate the formation of defects, particularly in the fluorescent-lamp coating process. A partial differential equation was derived based on the Navier-Stokes equation, using the lubrication approximation for thin layers. The effect of temperature distribution on surface-tension gradient was incorporated into the model, which enhances our ability to quantify defect formation in drying coatings. The results show that, temperature-induced surface-tension gradient plays a major role in defect formation. The effect of pressure gradient is negligible compared to the surface tension gradient in defect formation. A linear relation is observed between defect peak growth and time between t = 10 s and t = 500 s. Defect formation time also varies linearly with viscosity in the range between J..l = 0.1 P to 2 P. Parametric studies show that all the parameters studied have an effect on the defect. Temperature shows the greatest intluence in defect formation, followed by viscosity. This model can be used as a process analysis tool in industrial applications

SYNGAS PRODUCTION FROM GREENHOUSE GASES VIA DRM OVER Ni/Al2O3 CATALYST: EFFECT OF Ca ADDITION

In view of the escalating global warming phenomenon, utilization of CO2 has become an important event in recent decades. Syngas production via Dry Reforming of Methane (DRM) is one of the promising methods to produce COX-free hydrogen as a renewable and sustainable energy source. DRM requires an active functioning catalyst since it is a highly endothermic process. The catalytic behaviour of 10 wt.% Ni supported on Al2O3 and doped with CaO is investigated for DRM. In the present study, the effect of alkaline earth metal oxide (CaO) loading (varying from 0.5-2.0 wt.%) on the structure, properties, stability, and performances of the Ni-CaO/Al2O3 catalyst for the DRM process is studied. The catalysts were prepared by wet impregnation method and characterized by Scanning Electron Microscopy (SEM) to study the morphology of the fresh and spent catalyst and Thermogravimetric Analyzer (TGA), which changes in physical and chemical properties of the catalysts are measured as a function of increasing temperature and time. DRM is carried out in a fixed-bed reactor at a temperature range from 600°C to 800°C. Further, the effect of CH4 partial pressure on the conversion of CH4, CO2 and syngas ratio were also investigated. The thermal stability of the catalyst increased on loading with CaO, and CAT-4 (1.5 wt.% CaO, 8.5 wt.% Ni on Al2O3) displayed the optimum activity, stability, and least coke formation

Production of Biofuel via Hydrogenation of Lignin from Biomass

Historically, humans have been harnessing biomass as a source of energy since the time they knew to make a fire from woods. Even today, some countries still depend on woods as a main source of energy. Biologically, biomass contains carbon-, hydrogen- and oxygen-based matters that unify in a solid material and that are potentially to be converted to fuel. Lignin is one of the components present in lignocellulosic biomass and has been actively examined to be used for biofuel production. Issues arise with the chemical characteristic and rigidity of its structure, which a setback for its viability for biofuel conversion. However, such setbacks have been counteracted with the advances of lignin-based knowledge on its conversion to chemical precursors for biofuel conversion. Recently, investigations on hydrogenation as one of the chemical processes used can be potentially utilised for efficient and viable means for biofuel production

Activation of nano kaolin clay for bio-glycerol conversion to a valuable fuel additive

High production of biodiesel results in a surplus of glycerol as a byproduct that leads to a drastic decline in the glycerol price as well as overall biodiesel production. Alternative methods must be introduced for the economical process for biodiesel production via utilization of crude glycerol into valuable chemicals or fuel additives. This study introduces an ecofriendly process of solketal synthesis from glycerol and acetone in the presence of a novel metakaolin clay catalyst, which is a useful additive in biodiesel or gasoline, in order to enhance the octane number and to control the emissions. Moreover, kaolin clay catalysts are low cost, abundantly available, eco-friendly and one of the more promising applications for solketal synthesis. In this study, raw kaolin clay was activated with an easy acid activation technique, modification in physicochemical and textural properties were determined by using X-ray diffraction (XRD), Fourier Transform Infra-Red (FTIR) spectroscopy, Brunauer–Emmett–Teller (BET) and Field Emission Scanning Electron Microscope. Among all acid-treated catalysts, metakaolin K3 have shown best catalytic properties, high surface area and pore size after acid activation with 3.0 mol/dm3 at 98 °C for 3 h. Acetalization of glycerol with acetone carried out in the presence of an environmentally friendly and inexpensive novel metakaolin K3 catalyst. The maximum yield of solketal obtained was 84% at a temperature of 50 °C, acetone/glycerol molar ratio 6/1 and for 90 min with novel metakaolin clay catalyst. Effect of various parameters (time, temperature, acetone/glycerol molar ratio, catalyst loading) on the solketal yield and glycerol conversion was discussed in detail. This approach offers an effective way to transform glycerol into solketal—a desirable green chemical with future industrial applications

Determination of Optimum Condition for the Production of Rice Husk‐Derived Bio‐oil by Slow Pyrolysis Process

Recently, studies on bio‐oil have captured international interest in developing it as an alternative energy option. Bio‐oil which is also known as pyrolysis oil or bio‐fuel oil was produced by pyrolysis process without any additional oxygen. Biomass pyrolysis essentially converts 80–95% of the feed material to gases and bio‐oil. This chapter provides an overview of how to produce bio‐oil through slow pyrolysis of rice husk (RH) at different heating rates in order to determine the optimum reaction condition that will give maximum liquid yield. The characteristics of bio‐oil produced at different heating rates are then analyzed. The chemical compound of bio‐oil product was analyzed by using gas chromatography‐mass spectroscopy (GC‐MS). The bio‐oil produced at different heating rates is analyzed for its chemical composition. The higher number of phenol and acid compounds contributes to the higher pH number of bio‐oil that was produced at a heating rate of 20°C/min

Catalytic performance of bimetallic cobalt–nickel/graphene oxide for carbon dioxide reforming of methane

The design of economical and robust catalysts is a substantial challenge for the dry reforming of methane (DRM). Monometallic nickel-based catalysts used for DRM reactions had comparable activity to noble metals. However, they turned out to be less stable during the reactions. As a continuation of the interest in synthesizing catalysts for DRM, this paper evaluates the catalytic performance of bimetallic Co–Ni catalysts regarding their synergy effect, with graphene oxide (GO) as support for the first time. The synthesized bimetallic catalysts prepared via the wet-impregnation method were characterized using N2 physisorption analysis, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The catalytic test was performed in a stainless-steel tubular reactor in atmospheric conditions with a reaction temperature of 800 °C, time-on-stream (TOS) of 300 min and CH4: CO2 being fed with a ratio of 1:1. The bimetallic 10 wt%Co–10 wt%Ni/GO and 20 wt%Co–10 wt%Ni/GO catalysts had a similar BET specific surface area in N2 physisorption analysis. The XRD pattern displayed a homogeneous distribution of the Co and Ni on the GO support, which was further validated through SEM–EDX. The conversion of CO2, CH4, and H2 yield decreased with reaction time due to the massive occurrence of side reactions. High conversions for CO2 and CH4 were 94.26% and 95.24%, respectively, attained by the bimetallic 20 wt%Co–10 wt%Ni/GO catalyst after 300 min TOS, meaning it displayed the best performance in terms of activity among all the tested catalysts

Recent advances in cleaner hydrogen productions via thermo-catalytic decomposition of methane: Admixture with hydrocarbon

A continuous increase in the greenhouse gases concentration due to combustion of fossil fuels for energy generation in the recent decades has sparked interest among the researchers to find a quick solution to this problem. One viable solution is to use hydrogen as a clean and effective source of energy. In this paper, an extensive review has been made on the effectiveness of metallic catalyst in hydrocarbon reforming for COX free hydrogen production via different techniques. Among all metallic catalyst, Ni-based materials impregnated with various transition metals as promoters exhibited prolonged stability, high methane conversions, better thermal resistance and improved coke resistance. This review also assesses the effect of reaction temperature, gas hour space velocity and metal loading on the sustainability of thermocatalytic decomposition TCD of methane. The practice of co-feeding of methane with other hydrocarbons specifically ethylene, propylene, hydrogen sulphide, and ethanol are classified in this paper with the detailed overview of TCD reaction kinetics over an empirical model based on power law that has been presented. In addition, it is also expected that the outlook of TCD of methane for green hydrogen production will provide researchers with an excellent platform to the future direction of the process over Ni-based catalysts

Dry reforming of methane over Ni/KCC-1 catalyst for syngas production

Dry reforming of methane (DRM) is a trendy topic of investigation as a means of reducing global warming. However, the adoption of DRM for a commercial purpose is still a question due to the deactivation and sintering of catalysts. The performance of the 5Ni/KCC-1 catalyst by using the ultrasonic-assisted impregnation method was examined in this study. The micro-emulsion method and ultrasonic-assisted impregnation method were used to prepare KCC- 1 support and 5Ni/KCC-1 catalyst respectively. The catalyst was characterized by N2 adsorptiondesorption and field emission scanning electron microscopy (FESEM) techniques. FESEM morphology shows that KCC-1 support experienced a well-defined fibrous morphology in a uniform microsphere which can promote high catalytic activity. The results show that the catalyst has optimum performance with higher reactant conversions and H2/CO ratio when operated at 850oC in a tubular furnace reactor as compared to 750oC

Syngas production via bi-reforming of methane over fibrous KCC-1 stabilized ni catalyst

Bi-reforming of methane (BRM) technology has the potential to serve as an alternative energy source while also mitigating greenhouse gas emissions. However, the main hurdle in the commercialization of BRM is catalyst deactivation. In this study, the ultrasonic-assisted impregnation method was utilized to prepare a Ni-based catalyst supported on fibrous KCC-1 and tested in the BRM process. The prepared catalysts were characterized by XRD, BET, FESEM and TPR-H2 techniques to determine the textural and morphological properties of the catalyst. The catalytic performance was tested in a tabular fixed-bed continuous reactor at 800 °C with a stoichiometric feed ratio of 3:2:1 for CH4: H2O: CO2. For high nickel loadings, it was discovered that agglomerates of the Ni-active phase form on the surface of the support. The catalysts with a 10 wt% Ni content produced the best CO2 (79.2%) and CH4 (82.1%) conversions, as well as an optimum H2/CO = 1.62 ratio

Structural feature based computational approach of toxicity prediction of ionic liquids: Cationic and anionic effects on ionic liquids toxicity

yesThe density functional theory (DFT) based a unique model has been developed to predict the toxicity of ionic liquids using structural-feature based quantum chemical reactivity descriptors. Electrophilic indices (ω), the energy of highest occupied (EHOMO) and lowest unoccupied molecular orbital, (ELUMO) and energy gap (∆ E) were selected as the best toxicity descriptors of ILs via Pearson correlation and multiple linear regression analyses. The principle components analysis (PCA) demonstrated the distribution and inter-relation of descriptors of the model. A multiple linear regression (MLR) analysis on selected descriptors derived the model equation for toxicity prediction of ionic liquids. The model predicted toxicity values and mechanism are very consistent with observed toxicity. Cationic and side chains length effect are pronounced to the toxicity of ILs. The model will provide an economic screening method to predict the toxicity of a wide range of ionic liquids and their toxicity mechanism