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The existence of naphthenic acid (NA) in acidic crude oil tends to corrode the oil refinery equipment. In this study, a catalytic deacidification reaction involving the deacidifying agent and the synthesised catalyst was aimed to eliminate NA from acidic crude oil. Diethanolamine-polyethylene glycol (DEA-PEG) was introduced as a deacidifying agent. The wet impregnation method was applied for synthesizing the calcium oxide catalyst doped by copper supported on alumina (Cu/Ca/Al2O3). The potential catalyst was characterised utilising field emission scanning electron microscopy-energy dispersive X-ray (FESEM-EDX), Brunauer-Emmett-Teller (BET), and X-ray diffraction spectroscopy (XRD). The parameters include deacidifying agent dosing, loading dopant ratio and catalyst calcination temperature were performed to enhance the catalytic deacidification process in this study. Data showed that the total acidic number (TAN) value for crude B met the PETRONAS requirement for the TAN value below one using 1500 mg/L of DEA-PEG assisted by Cu/Ca (10:90)/Al2O3 catalyst.

The century of urbanisation and industrialisation had a great impact on the environment due to the rapid growth of the flue gas sectors. Thus, green technology is enforced to convert carbon dioxide (CO2) gas into methane (CH4) gas as an alternative fuel in electricity generation, particularly coal and natural gas sources. Cerium (Ce) was recognised as one of the most basic and unique redox characteristics utilised in the promising methanation reaction among catalysts used. The trimetallic catalyst used in this work was prepared with Ce as the based catalyst and ruthenium/magnesium (Ru/Mg) as the impregnated metal. Response surface methodology projected the CO2 conversion to be less than 0.3% of the experimental value of 78.82% using the indicated parameters of 593 °C calcination temperature and 61 wt.% ratios. Ru/Mg/Ce/Al2O3 catalyst with 60 wt.% of Ce loading calcined at 600 °C produced 58.08% of CH4. The characterisation results revealed that CeO2, Mg(Al2O4), and RuO2 species were the active species for CO2 methanation selectivity, as observed in XRD and XPS analyses. The mesoporous structure and particle agglomeration resulted in a surface area of 147 m2/g.

A novel trimetal-oxides (Ru/Fe/Ce) supported on γ-Al2O3 catalyst was synthesised by simple impregnation method and the activity was investigated at atmospheric pressure. The results showed that Ru/Fe/Ce (5:10:85)/γ-Al2O3 catalyst calcined at 1000 °C for 5 h was effective and gave a 97.20% of CO2 conversion at 275 °C with 93.5% of CH4 formation. The catalyst possesses medium-strength basic sites with the best reduction temperature of

A series of novel mixed metal oxide catalysts with the incorporation of copper as a dopant supported on zinc-alumina (Cu/Zn/γ-Al2O3) for biodiesel production have been synthesized and characterized. ZnO is a solid base catalyst, but its weak surface basic properties have limited the usage of ZnO in the transesterification reaction of refined used cooking oil to biodiesel. To further improve the catalytic activity, the copper dopant was loaded by the wetness impregnation method. Cu/Zn/γ-Al2O3 catalyst of 10:90 wt% dopant-to-based (ZnO) ratio with calcination at 800 °C exhibited the highest biodiesel yield (89.5%) at optimum reaction conditions (65 °C, 10 wt% catalyst loading, 1:20 oil-to-methanol mol ratio and 2 h reaction time). The N2 adsorption-desorption and CO2-temperature programmed desorption analyses indicated that the material possessed a high surface area (149 m2/g) and high basicity (3.7424 mmol/g). The mechanistic study confirmed the catalytic reaction followed the Langmuir-Hinshelwood (LH) model, which involves the initial adsorption of reactants molecules on active sites of the catalyst surface.

The world is challenged with depletion of non-renewable fossil fuel and environmental pollution. Thus, this research was emphasized on converting refined used cooking oil to safer and low toxicity biodiesel by base-catalyzed transesterification reaction. Alumina supported magnesium, calcium, strontium and barium oxide-based catalysts with iron as its dopant were optimized according to various calcination temperatures and iron loadings. The optimum conditions over potential catalyst was achieved with 20 wt% of Fe loading for Fe/Ba/Al2O3 catalyst calcined at 800 °C which gave the maximum biodiesel production of 84.02%. Characterization of catalyst carried out by XRD showed that the 20Fe:80Ba/Al2O3 catalyst calcined at 800 °C had a polycrystalline structure with high BET surface area (133.59 m2/g) while FESEM analysis displayed a morphology of uniform plate-like shape grains with fine particles in the range of 55–60 nm. CO2-TPD results showed that the catalyst exhibited highest basicity of 2.5854 mmol/g, while TGA analysis proved that 800 °C was the optimum calcination temperature. The transesterification process of refined used cooking oil to produce high yield biodiesel was effectively attained using 20Fe:80Ba/Al2O3 catalyst.

The utilization of carbon dioxide for methanization reactions in the production of synthetic natural gas (SNG) is of increasing interest in energy-related issues. The use of CO 2 as a raw material in methanization reactions in the formation of SNG is of increasing concern associated with energy problems. The effect of three independent process parameters (calcination temperature, ceria loading and catalyst dosage) and their interactions in terms of conversion of CO 2 was considered by response surface methodology(RSM). Box-Behnken design (BBD) revealed that the optimized parameters were 1000 °C calcination temperature, 85%wt ceria loading and 10g catalyst dosage, which resulted in 100% conversion of CO 2 and 93.5% of CH 4 formation. Reaction intermediate study by in situ FTIR showed that carboxylate species was the most active species on the catalyst surface. In-situ FTIR experiments revealed a weak CO 2 adsorption, that exist namely as carboxylate species over the trimetallic catalyst. As a result, dissociated hydrogen over ruthenium reacts with surface carbon, leading to *CH, which subsequently hydrogenated to produce *CH 2 , *CH 3 and finally to the desired product methane. The use of in situ-FTIR study indicated that the CO 2 methanation mechanism does not involve CO as a reaction intermediate. The more detailed mechanism of CO 2 methanation pathways involved over Ru-Fe-Ce/γ-Al 2 O 3 catalyst is discussed in accordance with IR-spectroscopic data. The better catalytic activity and stability over Ru-Fe-Ce (5:10:85)/γ-Al 2 O 3 catalyst calcined at 1000 °C showed the presence of moderate basic sites for CO 2 adsorption.

A series of cerium oxide based catalyst has been studied by various cerium loadings that calcined at 1000 o C using wet impregnation method. The potential Ru/Mn/Ce (5:35:60) /Al 2 O 3 catalyst calcined at 1000 o C was characterized using XRD, XPS, and BET analyses. As could be observed from the XRD analysis, at Ce ratio of 55% and 65%, both revealed the presence of RuO 2 with tetragonal phase and intense, sharper peaks indicating to high crystallinity and in line with lower surface area, 50.95 m 2 /g in BET analysis. Meanwhile, CeO 2 (cubic phase) and MnO 2 (tetragonal phase) were also observed for 55%, 60%, and 65%, respectively. However, the presence of Al 2 O 3 with rhombohedral phase at 55% and 65% was revealed as an inhibitor which decreased the CO 2 conversion. The presence of active species on Ru/Mn/Ce (5:35:60) /Al 2 O 3 catalyst has been confirmed using XPS analysis with the deconvolation peaks belonged to Ce 4+ with the formation of CeO 2 compound and Mn 4+ for MnO 2 . The product formed in catalytic methanation was proposed to be H 2 O and CH 3 OH from GC and HPLC analysis.

Environmental concerns in fossil fuel depletion intensified the search for alternate fuel from renewable resources. The focus of this study is to produce biodiesel from low-grade cooking oil by using Cu/Zn/γ-Al2O3 as bi-functional heterogeneous base catalyzed transesterification reaction. The investigation of Cu/Zn/γ-Al2O3 catalyst on the calcination temperatures, dopant ratios to zinc oxide based and number of alumina coatings had significantly affected the catalytic performance. The physicochemical properties examined by XRD, XPS and TEM analyses over Cu/Zn/γ-Al2O3 catalyst indicates polycrystalline structure dominated by cubic Al2O3, hexagonal ZnO and monoclinic CuO species that presumably acted as active species which contributed to the catalytic transesterification of biodiesel. The design of experiments was performed using Box-Behnken design coupled with response surface methodology in order to optimize Cu/Zn (10:90)/γ-Al2O3 catalyst preparation conditions. The experimental value achieved 88.82% production of biodiesel that closely agreed with the predicted value from RSM.

An estimated 2.2 billion people in 108 countries are expected to survive on multidimensional poverty and almost 1.5 billion out of 2.2 billion people survived on or less than US$1.25 a day. This review highlights the concept of a green economy that promotes an attractive green revolution to the present economic crises affecting developing countries for sustainable economic and environmental improvement. Green roads and highways can reduce the emissions released from fossil fuels and greenhouse gases if constructed with carbon neutral materials. Thus, carbon neutral materials used for the construction of green roads and highways can absorb temperature and excess emissions released by the vehicles because of their neutralities. This is because of the massive quantity of natural aggregates used during construction. Problems associated with green roads and highways made from carbon neutral materials are incompatibles with land use, geology, topography, substructure, landscape, rainfall, and other physical features. Therefore, physical features, geology, landscape, transportation, and development substructures were measured as crucial problems for national development. Most of the approaches used in this study are based on the context of a green economy and the development of green roads and highways. The USA possesses the highest GDP per capita of US$52,194.90 and Bangladesh possesses the lowest GDP per capita of US$1029.60. This implies that the GDP for USA is 50.70 times higher than that of Bangladesh. The study highlights positive solutions to the above global challenges. It can be concluded that global challenges will be addressed through the concept of green revolutions.

Carbon dioxide emission to the atmosphere is worsened as all the industries emit greenhouse gases (GHGs) to the atmosphere, particularly from refinery industries. The catalytic chemical conversion through methanation reaction is the most promising technology to convert this harmful CO2 gas to wealth CH4 gas for the combustion. Thus, supported neodymium oxide based catalyst doped with manganese and ruthenium was prepared via wet impregnation route. The screening was initiated with a series of Nd/Al2O3 catalysts calcined at 400 °C followed by optimization with respect to calcination temperatures, based ratios loading and various Ru loading. The Ru/Mn/Nd (5:20:75)/Al2O3 calcined at 1000 °C was the potential catalyst, attaining a complete CO2 conversion and forming 40% of CH4 at 400 °C reaction temperature. XRD results revealed an amorphous phase with the occurrence of active species of RuO2, MnO2, and Nd2O3, and the mass ratio of Mn was the highest among other active species as confirmed by EDX. The ESR resulted in the paramagnetic of Nd3+ at the g value of 2.348. Meanwhile nitrogen adsorption (NA) analysis showed the Type IV isotherm which exhibited the mesoporous structure with H3 hysteresis of slit shape pores. Keywords: Neodymium oxide, Methanation, Carbon dioxide, Natural gas, Greenhouse gases

Natural gas fuel is a green fuel and becoming very demanding because it is environmental safe and clean. Furthermore, this fuel emits lower levels of potentially harmful by-products into the atmosphere. Most of the explored crude natural gas is of sour gas and yet, very viable and cost effective technology is still need to be developed. Above all, methanation technology is considered a future potential treatment method for converting the sour natural gas to sweet natural gas.

Developed countries are increasing their demand for natural gas as it is an industrial requirement for fuel transportation. Most of modern society relies heavily on vehicles. However, the presence of CO2 gas has led to the categorization of sour natural gas which reduces the quality and price of natural gas. Therefore, the catalytic methanation technique was applied to convert carbon dioxide (CO2) to methane (CH4) gas and reduce the emissions of CO2 within the environment. In this study, samarium oxide supported on alumina doped with ruthenium and manganese was synthesized via wet impregnation. X-ray diffraction (XRD) analysis revealed samarium oxide, Sm2O3 and manganese oxide, MnO2 as an active species. The reduction temperature for active species was at a low reaction temperature, 268.2oC with medium basicity site as in Temperature Programme Reduction (TPR) and Temperature Programme Desorption (TPD) analyses. Field Emission Scanning Electron Microscopy (FESEM) analysis showed an agglomeration of particle size. The characterised potential catalyst of Ru/Mn/Sm (5:35:60)/Al2O3 (RMS 5:35:60) calcined at 1,000oC revealed 100% conversion of CO2 with 68.87% CH4 formation at the reaction temperature of 400oC. These results were verified by artificial neural network (ANN) with validation R2 of 0.99 indicating all modelling data are acceptable.

Converting the CO2 gas via catalytic methanation technology has significant potential application in the power plant industry. Therefore, ceria based catalyst impregnated with Ru/Mn/Al2O3 was developed and from the experimental results, the optimum conditions over potential Ru/Mn/Ce (5:30:65)/Al2O3 catalyst was achieved with 65 wt% of Ce based loading calcined at 1000 °C gave 97.73% of CO2 conversion with 91.31% of CH4 at 200 °C of reaction temperature. 10 g of the potential catalyst was pre-reduced at 300 °C for 30 min in the presence of H2 gas prior to the start of catalytic testing. The reliability, robustness, reproducibility and regeneration testing of this catalyst were further studied. The catalyst started to deactivate (spent catalyst) at sixth testing with only gave 41.17% CO2 conversion. However, the catalyst can be regenerated in the presence of compressed air at 400 °C for 3 h as it gave 92.85% of CO2 conversion. From the characterization of spent catalyst, the factor for the catalyst deactivation in this reaction was the particle agglomeration due to the loss of RuO2 and Mn2O3 species. When the catalyst was scale-up, the result showed that Ru/Mn/Ce (5:30:65)/Al2O3 catalyst able to convert 60% of CO2 and 50.4% of methane formation at lower reaction temperature of 160 °C.

The influence of preparation method for hybrid trimetallic oxide consisting mixture of TiO2 with SnO2 and WO3 were investigated. The physicochemical characteristics of the photocatalyst prepared by sol-hydrothermal, sol-immobilization and mechanical mixed methods were compared based on XRD, FESEM, TEM, HRTEM, DRUV, NA and XPS. Among the samples prepared by different methods, photocatalyst prepared by sol-hydrothermal exhibits the maximum catalytic activity for degradation of 1,2-dichlorobenzene in aqueous, followed by mechanical mixed sample. On contrary, an apparent deactivation of the photocatalyst was observed for sample prepared using sol-immobilization method. The excellent catalytic activity of photocatalyst by sol-hydrothermal could be attributed to the large amount of surface defects such as Ti3+, W5+ and oxygen vacancies as well as the existence of facets or structural defects. Detailed characterization of the photocatalysts allowed correlation of the activity with structural properties, crystallinity, morphology, charge transfer and surface defects. In addition, thorough study on data obtained from GC–MS and ATR-FTIR leads to a new possible reaction pathway for degradation of 1,2-dichlorobenzene in aqueous.

In this work, a series of supported manganese catalyst has been synthesized and utilized in oxidative desulfurization to remove 4,6-dimethyldibenzothiophene (4,6-DMDBT), dibenzothiophene (DBT) and ...

Catalytic methanation reaction has been a promising technique for the conversion of CO2 to valuable fuel product, CH4 and thus reduces the emission of CO2 to the environment. Many catalysts have been investigated by this method yet some carbon depositions have occurred during reaction which leading to low conversion rate of CO2 to CH4. Therefore, cerium catalyst has been applied in this study for the investigation of catalytic activity utilizing response surface methodology (RSM) method (Box-Behnken Design) in order to achieve the highest CO2 conversion. The potential trimetallic oxide catalyst of Ru/Mn/Ce (5:35:60)/Al2O3 was chosen and the experimental parameters used were calcination temperature of 600–800 °C, ratio based loadings of 60–80 wt%, and catalyst dosage of 3–7 g with CO2 conversion to CH4 as a respond. The RSM optimum parameter of calcination temperature of 697.47 °C, ratio of 60.38% and catalyst dosage 6.94 g was tested. At these conditions, the results were verified experimentally (99.98% CO2 conversion), which was accurately close to the predicted value (100% CO2 conversion). Ru/Mn/Ce (5:35:60)/Al2O3 catalyst revealed the active species of CeO2 in XRD analysis with oxidation state Ce 4+ as supported by ESR analysis. When the calcination temperature was increased, the surface area decreases as observed in nitrogen adsorption supported with larger particle size as shown in FESEM. The reducibility of cerium catalyst was started at lower temperature.

Photodegradation of 1,2-dichlorobenzene over illuminated trimetallic oxide consisting of rutile TiO 2 in major portion together with WO 3 and SnO 2 was studied with respect to the effect of physicochemical properties of the catalyst. The photocatalytic activity enhancement by the presence of surface defects due to calcination temperature was investigated with the information obtained from XRD, DRUV, PL, FESEM and XPS. Calcination of TiO 2 at 950 °C resulted in highest activity. Decrease in percentage of degradation of 1,2-dichlorobenzene was noted when it was immobilized on PVC film and chitosan beads. The effect of calcination temperature, catalyst loading and pH was investigated for slurry and after immobilization. Further optimization study was carried out with the aid of response surface methodology utilizing Box–Behnken design. High correlation was obtained for the experimental and the predicted value ( R 2 = 0.9992, Adj. R 2 = 0.9982 and Pred. R 2 = 0.9971). Optimization result showed that the maximum percentage of degradation was achieved at calcination temperature of 961.2 °C, with catalyst loading of 0.22 g and pH 7.2. The presence of two intermediates was identified during the reaction using GC–MS. On top of that the photocatalyst could also be reused for several times.

A simple method has been proposed for the removal and degradation of polychlorinated biphenyls (PCBs) from catches using low cost and environmental friendly way. The removal of PCBs from lipid layer to aqueous layer was done by utilizing polyethylene glycol (PEG) as phase transfer agent and photocatalysis technology for its degradation. Experimental involving various types of PEG and concentrations were performed to obtain the highest percentage of removal. The highest total amount of PCBs removal was attained using PEG 400 with concentration of 0.2 M. In order to determine the suitable photocatalyst to use for the degradation study, the physicochemical properties of WO3/SnO2/TiO2 prepared from mechanical mixed and sol-immobilization were compared. In situ and ex situ techniques were explored to determine its influence on removal and degradation of PCBs. Substantial degradation of removed PCBs in ex situ method was achieved in the presence of heterostructured WO3/SnO2/TiO2 photocatalyst prepared by mechanical mixing under visible light. Meanwhile significant total amount of PCBs reduction in mussels was observed under in situ method (with PEG 400, 0.2 M and photocatalyst) compared to control run. Thus, this study displayed conformity of the method with high degradation.

Attention continues to be focused on biomass as a very promising alternative source of renewable materials for energy production. This research focused on the use of a heterogeneous base alkaline earth metal oxide incorporated with a transition metal oxide catalyst supported on gamma alumina oxide varied with different temperatures, Cr loading and number of alumina coatings that make the biodiesel easily separated, low cost and environmental friendly. The physicochemical properties of Cr/Ca(10:90)/γ-Al2O3 catalyst calcined at 700 °C investigated by BET surface area and CO2-TPD indicated high surface area, 164.32 m2/g and higher basicity, 3.38 mmol/g, respectively. FESEM-EDX mapping showed the homogeneous distribution of each element presence in Cr/Ca(10:90)/γ-Al2O3 catalyst was well-distributed and indicated that the Cr/Ca has a higher dispersion on the surface of the γ-Al2O3. The response surface methodology was used to optimize the catalytic activity of Cr/Ca/γ-Al2O3 catalyst for transesterification of biodiesel from low-grade cooking oil. The most important variable for biodiesel yield was the calcination temperature of the catalyst followed by the Cr loading and the number of alumina coatings. The experimental value achieved with 93.10% conversion of biodiesel closely agreed with the predicted result from RSM and validated the findings of response surface optimization.

This study revealed that the existence of heterojunction of ZrTiO4/ZrTi2O6/TiO2 in the photocatalyst system has significantly enhanced the photodegradation of paraquat dichloride with respect to the increment of it thermal stability as shown in the XRD and XPS analyses. Several parameters such as ZrO2/TiO2 ratios (10:90, 20:80 and 30:70) and catalyst dosage (0.1–0.4 g) have been studied to achieve the optimum degradation of paraquat dichloride. The kinetic study was determined by using various ZrO2/TiO2 ratios calcined at 750 °C and showed that the photodegradation of paraquat over ZrO2/TiO2 photocatalyst follows a pseudo first-order kinetic. The optimum condition was obtained using ZrO2/TiO2 (20:80), calcined at 750 °C and with 0.3 g catalyst dosage which gave 84.41% degradation after 240 min under UV irradiation, λUV = 365 nm. The N2 adsorption–desorption analysis shows the mixture of Type III and IV isotherms with hysteresis loop type H2(b). Meanwhile, the Box–Behnken design showed the optimum photodegradation of paraquat was obtained at the calcination temperature of 750 °C, with the ZrO2/TiO2 ratio of 20:80 and 0.3 g catalyst dosage which was 0.24% lower than our experimental verification result.

The catalytic oxidative desulfurization (Cat-ODS) process has emerged as a new technology to achieve ultra-low sulfur levels in diesel fuels. Various cerium based catalysts impregnated with Mn/Al2O3 were developed in this study. The catalytic activity of Mn/Ce/Al2O3 was higher than the monometallic catalysts, Ce/Al2O3. Under these optimum conditions: tert-butyl hydroperoxide (TBHP)/sulfur ratio of 3, 5.26%Mn/11.68%Ce/Al2O3, temperature of 45 °C, 30 min of reaction, complete removal of model organosulfur compounds were obtained. In addition, >90% of sulfur was removed in commercial diesel. High resolution transmission electron microscopy (HRTEM) analysis of 5.26%Mn/11.68%Ce/Al2O3 showed the presence of Al2O3, CeO2 and MnO2. The active sites responsible for the higher oxidative desulfurization activity were CeO2 and MnO2. The mechanistic study showed that the reaction between TBHP and DBT was efficient to produce corresponding sulfone, instead of sulfoxide compound using 5.26%Mn/11.68%Ce/Al2O3 catalyst.

Bitumen is a heavy hydrocarbon sourced from petroleum refineries as by-product which is widely used as binder for flexible pavement. Bitumen is non-hazardous at room temperature but when heated to 165–200 °C to coat all the aggregates it generates hazardous fume which is severely detrimental to health. Consequences such as environmental degradation, depleting petroleum reserves and price spiking, led researchers to explore alternative sources of obtaining binder for flexible pavement. This research focused on the effect of adding waste cooking oil, tire rubber powder and palm oil fuel ash to reduce the percentage of bitumen in the mixture where palm oil fuel ash was applied as additive. These three modifiers are sourced from waste materials, easily available in the market and cheap in price. This method of recycling these waste materials solves the issue of littering and can ensure a cleaner environment. Laboratory investigations based on AASHTO and ASTM standard were performed to check physical and rheological properties of modified binders. Results were compared with neat bitumen as control sample to assess the feasibility of new mixture to be used in industrial scale. Outcome from this research shows that up to 15% replacement of bitumen is possible and this could produce equal or better performance in terms of stability, flow and rutting resistance. This work contributes directly to the field of transportation and highway in development of alternative binder for flexible pavement by introducing improved modified binder compositions using waste materials.

Naphthenic acids (NAs) tend to cause operational problems that can lead to the deactivation of catalysts. To overcome the problem, catalytic deacidification was introduced utilizing an ammonia solution in ethylene glycol with the aids of alkaline earth metal catalyst with alumina as a support. The initial total acid number observed for NAs in n-dodecane was 4.21 mg KOH/g. In total, 1,000 mg/L of 0.4% NH3-EG were used as the acid removal agent. Calcium, barium, and magnesium catalysts were tested in this study. The results showed Cu/Ca/Al2O3 was found to be the best catalyst that could be used to enhance the reaction.

The major contributor to global warming is human-generated greenhouse gases (GHGs) emissions that pollute the air. GHGs emissions are a global issue dominated by emission of carbon dioxide (CO2). Notably, CO2 accounts for an estimated 77% of GHGs and thus has a huge impact on the environment. The capture, sequestration, and utilization of CO2 emissions from flue gas are now becoming familiar worldwide. These methods are a promising solution to promote sustainability for the benefit of future generations. Previously, many researchers have focused on capturing and storing CO2; however, less effort has been spent on finding ways to utilize flue gas emissions. Moreover, several issues must be overcome in the field of carbon capture and sequestration (CCS) technology, especially regarding the cost, capacity of storage and the durability of the storage reservoir. In addition, this paper addresses new technology in carbon capture and sequestration. To make CCS technology more feasible, this paper suggests a sustainable method combining CCS and biofuel production using CO2 as a feedstock. This method offers many advantages, such as CO2 emission mitigation and energy security through the production of renewable energy. Due to the many advantages of biofuels, the conversion of CO2 into biofuel is a best practice and may provide a solution to pollution while encouraging sustainability practises.

Recently, there has been an increasing interest in green and renewable fuels due to the worldwide concern of an environmental crisis. So, this study focused on the synthesis, optimization and characterization of series of heterostructure Zn/Ca/Al2O3 catalysts with different parameters to test their effectiveness towards biodiesel production. The physicochemical properties of the potential catalyst were determined by BET, FESEM and CO2-TPD. The activity of the catalyst in transesterification reaction was evaluated at reaction temperature of 65 °C, 3 h reaction time, 6% (w/w) catalyst concentration and 1:24 M ratio of oil to methanol. The investigation of the synthesized Zn/Ca/Al2O3 catalyst showed that the calcination temperature, number of alumina coatings and dopant to base ratio have significant effects on the catalytic performance. These three critical parameters were investigated using response surface methodology (RSM) with Box Behnken design (BBD) to determine the optimum operating conditions for biodiesel production. From RSM study, the optimum conditions were 800 °C calcination temperature, 3 times alumina beads coating and 10:90 dopant to base ratio which gave 97.80% biodiesel conversion. From the F-value and low p-value (

Catalytic methanation is a fascinating method in converting the carbon dioxide gas from power plant flue gases into the valuable product of methane gas. It can be of great benefit to the environment and the national economy since the production of methane gas can be used as a fuel to run the turbine for electricity generation in power plant system or to run automobile vehicles. As such, catalytic methanation technology is able to reduce the emission of this greenhouse gas to atmosphere. Strontia based catalyst impregnated with Ru/Mn/Al2O3 was developed in this study. The optimum conditions over 10 g of Ru/Mn/Sr/Al2O3 catalyst were achieved with 65 wt% of based loading and calcined at 1000 °C for 5 h which gave 73.10% carbon dioxide conversion with 43.58% of methane at reaction temperature of 210 °C. The value was closely agreed with the predicted result obtained by Response Surface Methodology (RSM) which achieved 72.41% conversion. The higher carbon dioxide conversion was due to the higher reducibility and basicity of the catalyst surface as well as the higher surface area of 83.27 m2/g. The polycrystalline structure obtained from X-Ray Diffraction analysis showed a mixture of smaller (rod shape < 12 nm) and bigger (square sheet shape ∼130 nm) crystallite particles of alumina (Al2O3), strontia (SrO2), tetrastrontium diruthenate (Sr4(Ru2O9)), manganese (II,III) oxide (Mn3O4) and ruthenium oxide (RuO2). The active sites responsible for the higher carbon dioxide activity were SrO2 and RuO2.

The issue of elevated carbon dioxide (CO2) emissions levels is becoming critical as a topic of research. The quantification of CO2 has attracted the interest of researchers as they seek to determine the sources of CO2 that have an effect on the environment. Consequently, CO2 can be chemically transformed from a detrimental greenhouse gas into a renewable, valuable energy and it will be the future source of carbon fuels and hydrocarbon products. It requires a correct measure for quantification of greenhouse gases (GHGs) to tackle the situation as a real situation. Therefore, this paper aims to provide a holistic review of the quantification techniques to aid research in this field. Thus, the integration of a modelling method, empirical analysis, and a gas analyser for quantifying CO2 emissions are highly recommended as an avenue for future research. Therefore, this research will provide reliability and accuracy of carbon dioxide emission assessments and enhance the removal of excessive CO2 emissions from the atmosphere while delivering a low pollution energy source to the society towards the development of energy systems that are clean, efficient, and economical.

Carbon dioxide (CO2) emitted from different sources into ambient air is a major contributor to air pollution. In addition, long-term exposure in humans contributes to symptoms such as tiredness, weakness, memory loss, confusion, nausea, and loss of appetite. The separation and storage of CO2 are important parts of utilizing low-carbon energy, which is needed to cope with climate change. Cost-effectiveness is an important factor for determining an optimal carbon separation strategy. Several review papers on CO2 capture and storage are available, but in most of these publications only the theoretical and operational aspects appear, while cost and techno-economic evaluations are missing. In this paper, different techniques for CO2 capture and separation are thoroughly reviewed with a focus on the associated economic costs. Presently, chemical and physical methods are widely used for CO2 separation; however, the hope is to switch to more environmentally friendly methods. This review reveals that, although biological separation processes are regarded as safe and sustainable, these methods are still time-consuming and involve high bioreactor management costs for. Another important finding is that chemical membrane technology is promising due to its low cost and simple operation.

Naphthenic acids (NAs) is one of the major sources of corrosion in oil pipelines and distillation units in crude oil refineries. Removing NA compounds from crude oils is regarded as one of the most crucial processes in heavy oil upgrading. Catalytic deacidification method had been developed in order to reduce the total acid number values in crude oil. Crude oil from Petronas Penapisan Melaka had been chosen to be studied with original total acid number (TAN) of 2.43 mg KOH/g. The parameters used were different catalyst calcination temperatures, catalyst loading, reagent concentration, reaction times and reaction temperature. Acid removal agent of 2-methylimidazole in ethanol and monometallic calcium and cerium doped with alumina were used as a catalyst. The results showed that with the aid of catalyst, the TAN can be reduced to lower than 1 mg KOH/g. Catalyst of Ca/Al2O3 calcined at 900oC gave a better reduction than Ce/Al2O3 with 83.54% of TAN reduction (2.43 to 0.4) for Ca/Al2O3 catalyst and 71.19% (2.43 to 0.7) for Ce/Al2O3 catalyst. The best catalyst underwent several characterization methods such as X-Ray Diffraction Spectroscopy (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetry Analysis (TGA-DTA) for its physicochemical properties. It can be concluded that catalytic deacidification method was effective in extracting NAs from the crude oil thus lowered the TAN value to less than 1 mg KOH/g. Keywords: Naphthenic acids; Crude oil; Catalysts

A series of bimetallic nanocatalysts, cerium/iron oxides supported on the activated carbon (Ce/Fe-AC) were prepared by the impregnation method. Their catalytic activity in the oxidation of organosulfur in commercial diesel were investigated using tert-butyl hydroperoxide (TBHP) as an oxidant. The effect of reaction time, reaction temperature, dopant ratio and calcination temperature were studied to achieve optimum condition for sulfur removal efficiency. The results indicated that the Ce/Fe-AC (80:20) calcined at 400 °C was the most potential catalyst in this study and can remove 91.5% of sulfur under the optimum conditions. X-ray diffraction analysis (XRD) showed that the catalyst was highly amorphous, while micrograph of the field emission scanning electron microscopy (FESEM) illustrated an inhomogeneous distribution of various particle sizes composed of cerium and iron oxides as proven by energy dispersive X-ray analysis (EDX).A series of bimetallic nanocatalysts, cerium/iron oxides supported on the activated carbon (Ce/Fe-AC) were prepared by the impregnation method. Their catalytic activity in the oxidation of organosulfur in commercial diesel were investigated using tert-butyl hydroperoxide (TBHP) as an oxidant. The effect of reaction time, reaction temperature, dopant ratio and calcination temperature were studied to achieve optimum condition for sulfur removal efficiency. The results indicated that the Ce/Fe-AC (80:20) calcined at 400 °C was the most potential catalyst in this study and can remove 91.5% of sulfur under the optimum conditions. X-ray diffraction analysis (XRD) showed that the catalyst was highly amorphous, while micrograph of the field emission scanning electron microscopy (FESEM) illustrated an inhomogeneous distribution of various particle sizes composed of cerium and iron oxides as proven by energy dispersive X-ray analysis (EDX).

In this study, the effect of surface/structural defects of TiO2/SnO2/WO3 trimetallic oxide on the photocatalytic activity was investigated. Two sets of trimetallic oxide were prepared by mechanical mixing of the pure TiO2, WO3 and SnO2 with exposed facets synthesized by sol–gel and hydrothermal methods. These photocatalysts were characterized by XRD, DRUV, PL, FESEM, TEM and XPS. Comparison of the photocatalytic degradation of 1,2-dichlorobenzene was done under UV and visible light. The results showed that the trimetallic oxide prepared from hydrothermal exhibited higher photocatalytic activity under visible light compared to the sol–gel prepared photocatalyst. Based on the characterization, it could be deduced that the high photocatalytic activity was attributed to the synergistic effect of several factors such as the exposed facets, presence of Ti3+ and charge transfer (revealed by XPS) between the metal oxides through the heterojunction (from TEM image) formation. The charge transfer was further projected through a schematic diagram that showed the potential energy differences at the valence band and conduction band of the metal oxides.

Polybrominated diphenyl ether (PBDEs) are widely spread in the environment which posing elevated potential risks triggers world's attention due to their global distribution and accumulation in the environment and have been found to be a class of contaminants of concern. The present study involves the photocatalytic degradation of tetra (BDE-47), penta (BDE-99, BDE-100) and hexaBDEs (BDE-153, BDE-154) as the most utilized compounds in aqueous solution. The results analysed by gas chromatography-electron capture detector (GC-ECD) found that the degradation of PBDEs under UV light irradiation using the potential trimetallic oxide Cu/Ni10/TiO2 photocatalyst on the immobilized PVC underwent efficient degradation. The potential catalysts then were characterized using various physicochemical methods of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and diffuse reflectance ultraviolet visible (DR-UV Vis). Further optimization on the three critical parameters (TiO2 loading, calcination temperature and catalyst dosage) for PBDE degradation (BDE-47) were investigated using Box–Behnken experimental design. The optimized data obtained via BBD have found that the TiO2 loading (83 wt%, F-value = 33.60) is the most significant effective factor, followed by calcination temperature (800 °C, F-value = 10.18) and catalyst dosage (20 mg, F-value = 6.25) by giving 64.63% degradation of BDE-47 while the regression analysis was found to be as a satisfactory correlation between the experimental data and predicted values with R2 value of 0.9671 and Adj R2 of 0.9247. Interestingly, the potential photocatalyst of CuNi10Ti/PVC (5:10:85) demonstrated good activity which is suitable for industrial application.

The 65 wt% of ceria and strontia based catalysts prepared by impregnation with RuMn/Al2O3 were tested on its CO2 methanation reaction under reducing pretreatment at 300 °C. The result obtained revealed that the addition of Ce to RuMn/Al2O3 has a positive effect on the activity and catalyst stability compared to the Sr containing catalyst. The CO2 conversion over Ru/Mn/Ce-65/Al2O3 achieved 97.73% with 91.31% of methane formation at a reaction temperature of 200 °C while, 73.10% conversion over Ru/Mn/Sr-65/Al2O3 catalyst with 44.58% of methane yielded at reaction temperature of 210 °C. The characterization results obtained suggest that the CeO2, SrO2, RuO2, Mn2O3 and orthorhombic Al2O3 were the active species for both catalysts while, the presence of spinel compound, Sr4(Ru2O9) caused the reducibility and basicity of Ru/Mn/Sr-65/Al2O3 catalyst decreased hence reduced the catalytic activity eventually. The mechanistic study showed it was depended on the type of catalysts as the CO2 adsorbed on the Sr based catalyst tended to form monodentate carbonate at the initial state before forming the formate species when it was hydrogenated and finally releasing the methane. Meanwhile, the methane formation on Ce based catalyst involved the initially adsorption and dissociation of CO2 into C and O adsorbed species before reacting with the adsorbed H2 to form methane gas.

Decontamination of water sources by one-dimensional (1D) nanostructured TiO2 holds great potential due to their unique electronic and textural properties. In this study, CeO2-modified TiO2 nanotubes (Ce–TNTs) have been prepared by impregnation of CeO2 on hydrothermally synthesized TiO2 nanotubes (TNTs). The catalysts were characterized by XRD, HRTEM, EDX, STEM, EELS, DR-UV/VIS spectroscopy and nitrogen adsorption (NA) analyses. The photocatalytic activities of the synthesized Ce–TNTs were examined on the degradation of paraquat dichloride (PQ) under UV light. The modification of TNTs with CeO2 led to an enhancement of the photocatalytic activity. Box–Behnken design (BBD) based on response surface methodology (RSM) was used to optimize three experimental parameters namely; CeO2 ratio, calcination temperature and catalyst loading. ANOVA of the generated quadratic model yielded a coefficient of determination, R2 of 0.9926 and probability, P < 0.0001, which confirms that the model is suitable for predicting the optimum degradation efficiency of PQ. Based on this model, the calcination temperature and CeO2 ratio were the most significant parameters and the interactions between these parameters and the catalyst loading were also significant. The predicted optimum conditions that would give a maximum of 80.798% degradation of PQ in 4 h were 9.01% CeO2 ratio, 760.49 °C calcination temperature and 0.38 g catalyst loading. Validation experiments were conducted in triplicate and an average of 80.27% degradation of PQ was achieved which is in agreement with 80.798% predicted. Under these optimum conditions, TOC analysis showed that 51.10% mineralization of PQ was achieved within 4 h. Therefore, this work further confirms that the photocatalytic treatment of organics-contaminated water can be designed and optimized by RSM.

The catalytic oxidative desulfurization (Cat-ODS) is a process comprises of catalyst, oxidant and solvent for extraction. In this research, new catalyst formulation of alumina supported polymolybdate based catalyst was investigated in this research. Experimentally, the obtained results revealed that, Fe/MoO3–PO4(10:90)/Al2O3 calcined at 500 °C was the best and potentially catalyst in this study. The catalyst was able to reduce sulfur levels in commercial diesel from about 440 ppmw to 17.6 ppmw with 96% of total sulfur removal. Highest catalytic activity showed that the presence of phosphorus and ferum can significantly improve the catalytic activity of the molybdenum oxide catalyst. Temperature programme desorption (TPD) analysis showed that the Fe/MoO3–PO4(10:90)/Al2O3 catalyst calcined at 500 °C was strong lewis acid. 31P NMR analysis showed the presence of different phosphate species as calcination temperature was increased. The catalyst with the best activity showed high surface area of 239 m2/g. The oxidation mechanism was studied in detail, and based on our results, the oxidation reactivity of different substrates was in the following order: DBT>4,6-DMDBT>Th.

In recent times, there is a lot of concern regarding the presence and the concentration levels of harmful gases in the earth’s atmosphere due to the industrial energy combustion. Combustion occurs when fossil fuels, such as natural gas, fuel oil, coal or gasoline, react with oxygen in the air to produce heat. The heat from burning fossil fuels is used for industrial equipment such as boilers, furnaces and engines. Fossil fuels are hydrocarbons, meaning they are composed primarily of carbon and hydrogen. When fossil fuels are burned, carbon dioxide (CO2) and water (H2O) are the principle chemical products, formed from the reactants carbon and hydrogen in the fuel and oxygen (O2) in the air. The combining of oxygen in the air and carbon in the fuel to form carbon dioxide and generate heat is a complex process, requiring the right mixing turbulence, sufficient activation temperature and enough time for the reactants to come into contact and combine. Unless combustion is properly controlled, high concentrations of undesirable products can be formed. For example, carbon monoxide (CO) and soot can be formed resulting from poor fuel and air mixing or too little air. Other undesirable products, such as nitrogen oxides (NO, NO2), form in excessive amounts when the burner flame temperature is too high. If a fuel contains sulphur, sulphur dioxide gas (SO2) is formed. For solid fuels such as coal and wood, ash could be forms from incombustible materials in the fuel. The importance of energy combustion analysis is it can monitor the exhaust flue gas and atmospheric pollution from industrial emission. In order of that, this paper will give an overview on the measurement, method, and calculation of these pollutant in combustion analysis. However, it will focus on the two types of measurement techniques which are on-site emission measurement and laboratory testing measurement. The combustion analysis method offers many advantages such as improving fuel economy, reduce undesirable exhaust emissions and improve the safety of fuel burning equipment. A combustion analysis is highly recommended to be implemented in order to achieve sustainable development, especially in developing countries focusing on industrial development.In recent times, there is a lot of concern regarding the presence and the concentration levels of harmful gases in the earth’s atmosphere due to the industrial energy combustion. Combustion occurs when fossil fuels, such as natural gas, fuel oil, coal or gasoline, react with oxygen in the air to produce heat. The heat from burning fossil fuels is used for industrial equipment such as boilers, furnaces and engines. Fossil fuels are hydrocarbons, meaning they are composed primarily of carbon and hydrogen. When fossil fuels are burned, carbon dioxide (CO2) and water (H2O) are the principle chemical products, formed from the reactants carbon and hydrogen in the fuel and oxygen (O2) in the air. The combining of oxygen in the air and carbon in the fuel to form carbon dioxide and generate heat is a complex process, requiring the right mixing turbulence, sufficient activation temperature and enough time for the reactants to come into contact and combine. Unless combustion is properly controlled, high concentratio...

Deep oxidative desulfurization of model diesel consisting of thiophene, dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was investigated with various oxidants followed by extraction step using dimethylformamide (DMF). Response surface methodology based on Box–Behnken design was used to evaluate the effects of the main operating parameters, including the oxidant to sulfur molar ratio (2.0–4.0), oxidation temperature (40–60 °C) and oxidation time (10–60 min), on the 4,6-dimethyldibenzothiophene conversion. Among the oxidants used; tert -butyl hydroperoxide (TBHP) was led to the highest oxidation of model sulfur compounds. Meanwhile, the statistical results revealed that TBHP/sulfur ratio was the most important parameter followed by oxidation time and oxidation temperature. The optimum oxidative desulfurization conditions for 4,6-DMDBT conversion had been attained at TBHP/sulfur ratio of 3.0, temperature of 48 °C and period time of 31 min, respectively with the highest conversion of 4,6-DMDBT of 84.5%. The experimental optimum yield fitted-well with the predicted value with less than 5% error. The mechanistic study showed that the reaction between TBHP and 4,6-DMDBT was efficient to produce corresponding sulfoxide, instead of sulfone compound.