KNO3-Loaded Coffee Husk Ash as a Heterogeneous Alkali Catalyst for Waste Frying Oil Valorization into Biodiesel

Modeling and simulation of Khat waste fast pyrolysis for energy recovery

Bioenergy is now recognized to be capable of providing the vast majority of predicted future renewable energy supply. Biomass is currently considered a common and commonly used renewable energy source. This study depends upon the investigation of khat waste using Aspen Plus software, which is required for creating environmentally friendly energy sources capable of improving our access to energy and economic sustainability. The outcome of the study is to understand the characteristics of the pyrolysis process without conducting a time-consuming, expensive, and complex procedure. The results of the investigation will be useful in determining the best feedstock for the formation of biofuel. Aspen Plus software simulates several ash-free organic components, including carbon, oxygen, nitrogen, hydrogen, and sulfur, with results like 45.72 % for carbon, 5.84 % for hydrogen, 0.43 % for nitrogen, and 38.56 % for oxygen. The production of biofuel is affected by processing parameters such as temperature and total mass flow rate. During reactions with the same mass but different temperatures, the bio-oil declined from 600 °C to 800 °C, while the maximum gas emission climbed quickly and the biochar reduced. In addition, it was recovered from Khat waste and proved to have an energy efficiency of 80.75 % and a net energy capacity of 134.25 kW. In addition, the High heating value (HHV) can be obtained from Khat waste is 19.38 MJ/kg, and low heating (LHV) can be 18.12 MJ/kg. We have been able to realize it using the Institute of Gas Technology formula based on ultimate analysis. The results show that Khat produces more oil than other wastes. As a result, all Khat waste is naturally occurring and Khat waste usually contains less nitrogen and no sulfur when used as fuel, which is an air pollutant reducing and protecting the environment.

OH-Impregnated Household Bleach-Making Sediments for the Catalysis of Waste Cooking Oil Transesterification: Parameter Optimization

Industrial and academic societies have been bothered with the generation and subsequent management of residues settled out from household bleach, due to its corrosive properties. Therefore, the aim of this research was to introduce a NaOH-impregnated calcium-based solid catalyst from the aforementioned sediments for waste cooking oil transesterification. To prepare the catalyst (RC-ITB), the wet impregnation technique was followed and successfully characterized via X-ray diffraction (XRD), X-ray fluorescence(XRF), differential scanning calorimetry (DSC), Brunauer-Emmett-Teller (BET), Fourier transform infrared (FT-IR), and scanning electron microscopy (SEM) methods. The study findings suggested that RC-ITB has a BET surface area of 9.312 m2 g-1 and is largely made up of calcium with its compound forms such as carbonates, hydroxides, and oxides. The evaluation of pH values verified that RC-ITB is more alkaline (i.e., pH = 12.65) relative to its precursor RC (pH = 10.66), largely attributable to OH impregnation. To study the catalytic performance, three numeric factors with three levels of treatment were used, and their influences were analyzed through a response surface approach. Accordingly, the optimal yield of biodiesel was found to be 80.04% at a reaction temperature of 61 ± 2 °C, catalyst weight of 6.33 wt %, and a molar ratio of 23.94. Moreover, FTIR analysis verified that the glycerol part of triglycerides had been replaced with a methoxyl unit. Also, the fuel quality parameters of the FAME product were examined, including density, kinematic viscosity, acid value, density, cetane number, cloud point, saponification value, and pour point; all of these values fall within the ASTM D6751-accepted limits. Thus, the findings showed that the sediments of household bleach production could be a candidate source to explore heterogeneous basic catalysts.

Catalytic Performance Investigation of Alkali and Bifunctional Catalysts Derived from Lignocellulosic Biomasses for Biodiesel Synthesis from Waste Frying Oil

In this study, alkali and bifunctional catalysts were synthesized for waste frying oil methyl ester (WFOME) synthesis. Coffee husk (CH) and CH blended with Eragrostis tef straw (TS) (CH-TS) lignocellulosic biomasses (LBs) were utilized during the catalysts' synthesis. The alkali catalysts were CH and CH-TS ashes, both modified by KNO3 impregnation. They are designated as C-45 and C-Mix, respectively. Zirconia (ZrO2) promoted CH ash catalysts via precipitation followed by impregnation (Bic-PP) and in situ precipitation-impregnation (Bic-Dm) were the bifunctional ones. CH and CH-TS chars were the supporting frameworks during the catalysts' composite materials (CCMs) preparation. The combustion performance of LBs and CCMs was evaluated and associated with the catalysts' physicochemical properties. Using XRD, SEM, FTIR, alkalinity, TOF, and BET surface area analysis, catalysts were characterized. The combustion performance of the LBs was in the order of TS > CH-TS > CH. Among CCMs, the highest combustion performance was for CCM-Mix (KNO3/(CH-TS char)) and the lowest was for CCM-45 (KNO3/ CH char). The C-Mix catalyst was a light green powder due to the reaction between inorganic components, whereas C-45 was dark gray due to the presence of unburned char. The CCMs for bifunctional catalysts had moderate combustion performance and yielded light gray powdered catalysts containing tetragonal ZrO2. The optimum WFOME yields were 98.08, 97, 92.69, and 93.05 wt % for C-Mix, C-45, Bic-Dm, and Bic-PP assisted WFO transesterification, respectively. The results were obtained at a reaction temperature of 65 °C, time of 1 h, and methanol to WFO molar ratio of 15:1 using catalyst amounts of 5 and 7 wt % for the alkali and bifunctional catalysts, respectively. The greatest moisture resistance was offered by the C-Mix catalyst. The best reusability was for the C-45 catalyst. Catalysts' deactivation modes include active site leaching and poisoning.

Valorization of calcium hypochlorite precipitate as a new source of heterogeneous catalyst development for biodiesel production: A preliminary experiment

One of the main problem related with liquid bleach production from calcium hypochlorite is the amount of precipitates generated and its consequent management. As a result, academic and industrial communities have been challenged with searching of a means for its valorization. Therefore, this research explores the application of the precipitate as a viable source of Ca-based heterogeneous catalyst development for the production of waste cooking oil methyl esters for the first-time. The catalyst was prepared by dividing the precipitates into three forms, viz. raw untreated (RC), heat treated (RC-TB), and NaOH impregnated plus thermally activated (RC-ITB). The prepared catalysts were efficiently characterized by XRF, XRD, FTIR, SEM, and BET techniques. The characterization results indicated that the catalysts are mainly composed of calcium metal in the form of oxides (CaO), calcite (CaCO3) and Portlandite (Ca(OH)2), which are the promising constituents of basic catalysts. The BET inspection of RC, RC-TB, and RC-ITB revealed the specific surface area of 8.509, 9.089, and 9.312 m2/g, respectively. At the same reaction conditions, the maximum biodiesel yield of 76.05 % was achieved by RC-ITB compared to RC-TB (62.57 %) and RC (19.74 %), because it's larger specific surface area and highest basic nature (pH = 12.65 at 1:5 w/v) improves the reaction catalysis through better catalyst-substrates interactions. The lower biodiesel yield was attained through the RC catalyst due to its untreated surface, lower specific area, and weak alkaline nature (pH value = 10.66 at 1:5 w/v). Furthermore, regardless of the amount of yield, almost similar fuel properties and functional groups of the products over the coded catalysts were observed. Generally, the possibility of calcium hypochlorite precipitate as a precursor of Ca-based heterogeneous catalyst has been effectively proven in this research, which could be very important for environmental safety and industrial resource integration.