Pyrolytic-deoxygenation of triglycerides model compound and non-edibleoil to hydrocarbons over SiO₂-Al2O₃ supported NiO-CaO catalysts

Catalytic deoxygenation (DO) of triglycerides-based feeds to diesel-like fuel was investigated over NiO-CaO/SiO₂-Al2O₃ and NiO/SiO₂-Al2O₃ catalysts using semi-batch reactor under partial vacuum and inert N₂ flow. The results showed that the bi-functional catalyst exhibited the highest DO activity with product selectivity toward diesel-like fuel n-(C₁₃–C₂₀). The catalytic process appeared to inhibit the occurrence of side reactions via neutralization of the strong acid sites. On the other hand, DO reaction under inert N₂ flow has improved the deoxygenated product, which demonstrate that N₂ flow condition has effectively removed the decarboxylation/decarbonylation gasses (CO₂/CO) from poisoning the catalyst active sites. The high concentration of strong basic-acid sites of the catalyst is the main reason for increased CC cleavage pathway, while milder acidic sites responsible for CO cleavage pathway. High degree of unsaturated fatty acid in the feedstock has affected adversely the DO of triglycerides by accelerating the catalyst deactivation. The N₂ flow condition, degree of unsaturated fatty acid in the feedstocks, acidity and basicity of the catalysts are important factors to improve DO activity as well as product selectivity

Carbon dioxide sorption by tetradecylamine supported on silica gel

Carbon dioxide emissions generated from fossil fuel-based power plants and other industries has reached 400 ppm in atmosphere. This negatively impact the environment, infrastructures and wildlife in particular. A lot of efforts are needed to produce CO2 gas sorbent in order to reduce high CO2 concentration. Therefore, porous silica gel (SG) is modified with amine compound for carbon dioxide capture. Calcinated silica gel functionalized with tetradecylamine (TDA) using wet impregnation has been developed as a porous media. The prepared sorbents is characterized by N2 physisorption technique Brunauer-Emmet-Teller analysis (BET). Significant changes in physical properties of the sorbents further ascertained the dispersion of TDA on the internal channels and external surface of the SG. Reactivity of porous sorbent towards CO2 was evaluated using isothermal CO2 adsorption desorption technique. This study shows 65TDA/SG enable to adsorb CO2 in the highest capacity which is 23.22 cm3CO2per gram sorbent. Moreover, CO2 capture consists of two type sorption which are physisorption and chemisorption. 55TDA/SG is the best sorbent in capturing CO 2by chemisorption (19.62 cm3CO2per gram adsorbent)

Hydrogen production from wood gasification promoted by waste eggshell catalyst

Bio-hydrogen renowned as a future potential hydrogen source and studies were devoted in developing the efficient way to obtain the hydrogen. Biomass gasification of Azadirachta excelsa wood was carried out with addition of naturally derived CaO catalyst using temperature-programmed gasification (TPG) technique. The reaction (TPG) was performed at 50–1000°C in 5% O2/He with flow rate 10 ml/min, and the product gas evolution (H2, CH4, CO and CO2) was detected by online mass spectrometer. The waste eggshell was chosen as a natural source of CaO, and the effect of catalyst loading was investigated in this study. All the fresh and used catalysts were characterized, and the physicochemical changes of the eggshell were observed through scanning electron microscopy, X-ray fluorescence and X-ray diffraction techniques. Hydrogen yield were increased along with the catalyst loading (20%, 40% and 60%) from 57 to 73%, respectively, compared to the reaction without catalyst. The additions of waste eggshell enhanced the catalytic activity and suppressed CO2 production through CaO absorption property which induced the water gas shift reaction that promotes H2 production at lower temperature

Performance of NiO Doped on Alkaline Sludge from Waste Photovoltaic Industries for Catalytic Dry Reforming of Methane

Alkali sludge (AS) is abundantly waste generated from solar PV solar cell industries. Since this potential basic material is still underutilized, a combination with NiO catalyst might greatly influence coke resentence, especially in high-temperature thermochemical reactions (Arora and Prasad 2016). This paper investigated alkaline sludge containing 3CaO-2SiO₂ doped with well-known NiO to enhance the dry reforming of methane (DRM) reaction. The wet-impregnation method was carried out to prepare the xNiO/AS (x = 5–15%) catalysts and tested them to determine their physicochemical properties. The catalytic performance of xNiO/AS catalysts was investigated in a fixed bed reactor/GC-TCD at a CH₄ : CO₂ flow rate of 30 ml− 1 during a 10h reaction by following (Shamsuddin et al. 2021c). For optimization parameters, the effects of NiO concentration (5, 10, and 15%), reaction temperature (700, 750, 800, 850, and 900°C), catalyst loading (0.1, 0.2, 0.3, 0.4, and 0.5g), and GHSV (3000, 6000, 9000, 12000, and 15000h− 1) were evaluated. The results showed that while physical characteristics such as BET surface area and porosity do not significantly impact NiO percentages of dispersion and chemical characteristics like reducibility are crucial for the catalysts' efficient catalytic activity. Due to the active sites on the catalyst surface being more accessible, increased NiO dispersion results in higher reactant conversion. The catalytic performance on various parameters shows 15%NiO/AS exhibits high reactant conversion up to 98% and 40–60% product selectivity in 700oC, 0.2g catalyst loading, and 12000h− 1 GHSV (see Fig. 1). According to spent catalyst analyses, the catalyst is stable even after the DRM reaction. Meanwhile, increased reducibility resulted in more and better active site formation on the catalyst. Synergetic effect of efficient NiO as active metal and medium basic sites from AS enhanced DRM catalytic activity and stability with low coke formation

Comparative adsorption isotherm for Beryllium oxide/Iron (III) Oxide toward CO2 adsorption and desorption studies

Surface modification of Fe2O3 by adding BeO was synthesized and calcined at different temperatures of 200-600 °C. The adsorbents were characterized by using XRD, N2 adsorption-desorption isotherm prior to performing CO2 adsorption and desorption studies. The CO2 adsorption data were analyzed using adsorption isotherm models such as Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich. BeO/Fe2O3-300 that calcined at 300 °C showed the most efficient adsorbent with physisorption and chemisorption were measured at 5.85 and 45.88 mg/g respectively. The CO2 adsorption notably best fitted with Freundlich isotherm with R2 = 0.9897 and calculated adsorption capacity closest to experimental data. This implies the CO2 adsorption process was governed by multilayer adsorption on the heterogeneous surface of the adsorbent. The mean free energy of adsorption (E=3.536 kJ/mol) from Dubinin-Radushkevich and heat of adsorption (bT=3.219 kJ/mol) from the Temkin model support that the adsorption process is physical phenomena

CO2 capture on NiO supported imidazolium-based ionic liquid

CO2 capture on NiO supported imidazolium-based ionic liquid, NiO/[emim][HSO4]/SiO2 as an adsorbent was investigated using gas adsorption analyzer and physicochemical properties of the adsorbent were characterized using X-ray powder diffraction (XRD), surface area analyzer (BET method) and temperature-program-desorption analysis (TPD). Immobilization of ionic liquid on silica, [emim][HSO4]/SiO2 slightly decreased the surface area compared to bare silica from 266 to 256 m2/g due to the pore blocking by the confinement of IL in SiO2 pore. Interestingly, introduction of NiO on supported ionic liquid, NiO/[emim][HSO4]/SiO2 was increased the surface area as well as pore volume from 256 to 356 m2/g and 0.14 to 0.38 cm3/g, respectively. The enhancement of surface area and pore volume was significantly increased the CO2 adsorption performance with capacity of 48.8 mg CO2/g adsorbent compared to [emim][HSO4]/SiO2 27.3 mg CO2/g adsorbent)

Characterizations and application of supported ionic liquid [bmim][CF3SO3]/SiO2 in CO2 capture

Supported ionic liquid (IL) [bmim][CF3SO3] on SiO2 was prepared, characterized and its potential evaluated for CO2 capture via adsorption and desorption studies using gas adsorption analyzer. The physical and chemical properties were determined using N2 adsorption/desorption and CO2-TPD analysis. The increasing IL loading caused a drastic decrease in the surface area as well as pore volume due to the confinement of IL within the micropore and mesopore area. However, the increasing IL loading increased the basicity of the sorbent which significantly enhanced CO2 chemisorption. Supported [bmim][CF3SO3] on SiO2 revealed the physical and chemical adsorption of CO2 and resulted in a remarkable CO2 adsorption capacity at atmospheric pressure and room temperature (66.7 mg CO2/gadsorbent) which has great potential in industrial applications

CO2 capture using ionic liquid hybrid sorbent: physical and chemical adsorption-desorption study

A hybrid sorbent of ionic liquid immobilized silica could enhance the adsorption capacity of CO2 capture compared to ionic liquid itself. This study emphasizes the physical and chemical adsorption-desorption study using 1-butil-3-methylimidazolium trifluoromethanesulfonate immobilized on silica, [bmim][CF3SO3]/SiO2. Different loading (1–10% mol/mol) of [bmim][CF3SO3] on silica were synthesized using sol-gel method. This work shows the most efficient adsorbent of 1%[bmim][CF3SO3]/SiO2 exhibits an adsorption capacity of 73.88 mg CO2/g. CO2 capture is dependent on the physical and chemical properties of the [bmim][CF3SO3]/SiO2 hybrid sorbent system. The studied shows the physical adsorption of CO2 is controlled by the porous nature of the sorbent. The formation of micro-partial pores on 1%[bmim][CF3SO3]/SiO2 is a major factor that contribute the higher physical adsorption capacity of CO2. Meanwhile, chemical properties i.e the base strength of the sorbent was found to affect the chemical adsorption-desorption of CO2. The presence of anions which consist of fluroalkyl functional group enhanced the capacity adsorption of CO2. There is a mixture between CO2 and CO was found during the chemical desorption process which indicates the occurrence of CO2 released and decomposition of [bmim][CF3SO3] at medium range temperature of 450–500 °C due to the Boudouard reaction. The sorbents used in this work were characterized using BET method, FTIR, and FESEM