Production of Ethylene From Ethanol Dehydration Over H3PO4-Modified Cerium Oxide Catalysts = Penghasilan Etilena Daripada Pendehidratan Etanol Dengan Mangkin Serium Oksida Terubahsuai H3PO4

Production of ethylene from ethanol dehydration was investigated over H3PO4 (10 wt.% to 30wt.%)-modified cerium oxide catalysts synthesized by wet impregnation technique. The prepared catalysts were characterized using scanning electron microscope (SEM), N2 adsorption-desorption method, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) for the physicochemical properties. The ethanol catalytic dehydration was carried out in a fixed-bed reactor at 673-773 K and at ethanol partial pressure of 33 kPa. The effects of phosphorus loading on catalyst and reaction temperatures were investigated in terms of catalytic activity towards product selectivity and yield. Overall, the selectivity and yield of ethylene increased with the temperature and phosphorus loading. The highest ethylene selectivity and yield were 99% and 65%, respectively, at 773 K and 33 kPa over the 30 wt.% H3PO4-modified cerium oxide

Catalytic Performance of Commercial Zeolites Y as Catalyst for Ethylene Production from Ethanol Dehydration

Catalytic dehydration of ethanol into ethylene was studied over commercial Zeolites-Y with different Si:Al ratios between 5.1:1 and 80:1, and temperature from 573 K to 773 K. The physicochemical properties of fresh and spent catalyst of Zeolite Y Si:Al 80:1 (best performing catalyst) were investigated using N2-physisorption, TGA, SEM-EDX, NH3-TPD, FTIR and XRD. Results showed that catalysts with higher Si:Al ratios exhibit better catalytic performance in terms of higher ethanol conversion and higher selectivity to ethylene. Indeed, zeolites-Y with Si:Al ratio 5.1:1 and 12:1 demonstrated low catalytic activity with ethanol conversion of 34% and 2%, respectively. However, ethylene selectivity of NH3-Y (5) was 84%, which was considerably higher than NH3-Y (12) which was 26%, indicated that this catalyst was not promoting the formation of other hydrocarbons i.e. methane and ethane. Albeit all of the catalysts namely H-Y (30), H-Y (60) and H-Y (80) showed favorable performance in ethanol dehydration, H-Y (80) attained almost total selectivity to ethylene and highest conversion of 73.0% among all the tested catalysts

Green reduction of graphene oxide by using phtoextracts from banana peels

Graphene is a 2-dimensional (2D) material that attracts many researches interest due to its significant properties and applications. Graphene can be synthesize from oxidation of graphite flakes and reduced by using reductant to become graphene nanosheets. Graphene oxide can be reduced chemically by using reducing agents such as hydrazine or dimethlyhydrazine. However, these chemicals are highly poisonous and toxic, which will bring harmful effect to human beings and environment. Therefore great care is needed when handling these materials and it requires extra routes to remove the impurities introduced by the chemical reduction of graphene oxide such as C-N. To ease the synthesis of good quality and environment friendly graphene, green reduction of graphene oxide becomes an alternative way. In this study, phytoextracts from banana peels was used as the reducing agent due to its high phenolic contents and antioxidant activity. Graphite oxide was fabricated using graphite flakes before undergoing ultrasonication for exfoliation to form the graphene oxide. The graphene oxide was reduced by using phytoextracts from banana peels at room temperature and refluxed temperature. Optimization of phytoextracts reduction was carried out by varying the phytoextracts concentration, reduction time and reduction temperature. The graphene oxide and graphene were characterized by using Ultraviolet-visible spectrophotometer (UV-Vis), Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and cyclic voltammetry analysis (CV) for the fabrication of glucose sensor. UV-Vis result for graphene oxide shows an absorption peak at range of 230 nm and red-shifted to 270 nm for phytoextract reduced graphene oxide (PRGO). Graphite oxide (GO) in FTIR study shows intense band at 1623 cm-1 (C=O stretching), 1053 cm-1 (for C-O stretching), and a broad band around 3332 cm-1 for hydroxyl group. PRGO shows the a decrease in the intensity at 3332 cm-1, but does not remove the peak at 1052 cm-1 and 1623 cm-1. PRGO also exhibits a comparable solubility as conventional reduced graphene oxide and in the application of glucose sensor; PRGO was able to detect a glucose concentration of 0.1 mM by using glassy carbon electrode (GCE) at a scan rate of 50 mVs-1

Ethylene production from ethanol dehydration over non- modified and phosphorus modified zeolite Y

Ethylene is an important raw material for the downstream petrochemical industry. Significantly, with the shortage of natural resource and fossil fuel-derived energy, catalytic dehydration of ethanol to ethylene route has become compelling, and therefore has been drawing attention lately. In this work, commercial zeolite Y was screened to identify the best Si/Al ratio as well as analyze the catalysts’ physicochemical properties. Besides, zeolite Y and phosphorus modified zeolite Y were employed as catalysts to study the effect of reaction temperatures and ethanol partial pressure on dehydration of ethanol to form ethylene. Towards achieving this goal, zeolite Y with various Si/Al ratio (5.1:1. 12:1, 30:1, 60:1 and 80:1) were firstly screened; zeolite Y with Si/Al ratio 80:1, coded H-Y (80) demonstrated the best catalytic performance with high ethanol conversion and ethylene selectivity (73.0% and 99.5% respectively) at 773 K. Subsequently, wet impregnation technique was employed to modify the H-Y (80) with phosphoric acid solution. For activity evaluation, a bench-scale fixed-bed reactor was employed and only the gaseous product from ethanol dehydration was collected and subjected to GC analysis. From the results obtained, BET specific surface area of fresh catalysts showed decreasing trend with increasing phosphorus loadings. Moreover, phosphorus modification on H-Y (80) can decrease the volume of micropores and mesopores due to channel blocking by PO43-. In addition, the NH3-TPD analysis showed that the increase in phosphorus loading had increased the moderate-strong acid sites. Among all the phosphorus modified H-Y (80), 3.15P/H-Y (80) was shown to exhibit the highest ethanol dehydration activity, where the conversion of ethanol at 773 K was 66.45%. The ethylene selectivity over all the catalysts was almost similar, easily attaining values of greater than 88.0%. Based on the N2 physisorption and SEM-EDX analysis of spent catalysts, it can be confirmed that the there was less carbon deposition on phosphorus modified H-Y (80) and demonstrated a better stability during the reaction although this has come at the expense of reduced activity. In conclusion, H-Y (80) showed the best catalytic activity among all the tested zeolite Y, and phosphorus modification decreased the BET specific area but increase the strength of acid sites in the catalysts. From the results, high reaction temperature and low ethanol partial pressure favour ethanol dehydration by H-Y (80)

Catalytic Ethylene Production from Ethanol Dehydration over Non-Modified and Phosphoric Acid Modified Zeolite H-Y (80) Catalysts

The present work reports on the effects of phosphoric acid-modified Zeolites-Y towards the ethylene formation from ethanol dehydration. The catalyst was impregnated with different H3PO4 loadings from 10 to 30wt%. All the catalysts were characterized using N2-physisorption, thermogravimetric analysis, NH3-TPD, FTIR, SEM-EDX, X-ray diffraction and XPS techniques. The non-modified Zeolite-Y with Si/Al 80:1, H-Y (80) was found to exhibit excellent catalytic activity owing to the presence of weak acid sites that was able to protonate the hydroxyl group of ethanol. Although ethanol conversion dropped with phosphorus modified catalysts, it was found that the modified Zeolite-Y with 10wt% H3PO4 can achieve 99% selectivity to ethylene at 723 K and ethanol partial pressure of 16 kPa. Overall, ethanol conversion and ethylene selectivity decreased in the order of H-Y (80)> 10P/H-Y (80) > 20P/H-Y (80) > 30P/H-Y (80). The decrease in ethanol dehydration activity of phosphorus modified catalysts can be ascribed to the reduced BET specific surface area and pore volume due to the surface coverage by layers of H3PO4, consequently, hindered ethanol access to the active site However, the spent phosphorus modified Zeolite-Y catalyst consistently showed less carbon formation compared to the undoped catalyst. This could be due to the reduction in strong acid site and also hindrance of C2H5OH from travelling deep into the pore networks of H-Y (80), therefore reducing the residence time with a consequence of minimizing the carbon laydown

Production of Ethylene from Ethanol Dehydration over H3PO4-Modified Cerium Oxide Catalyst

Production of ethylene from ethanol dehydration was investigated over H3PO4 (10wt% to 30wt%)-modified cerium oxide catalysts synthesized by wet impregnation technique. The prepared catalysts were characterized using scanning electron microscope (SEM), N2 adsorption-desorption method, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) for the physicochemical properties. The ethanol catalytic dehydration was carried out in a fixed-bed reactor at 673-773 K and at ethanol partial pressure of 33 kPa. The effects of phosphorus loading on catalyst and reaction temperatures were investigated in terms of catalytic activity towards product selectivity and yield. Overall, the selectivity and yield of ethylene increased with the temperature and phosphorus loading. The highest ethylene selectivity and yield were 99% and 65%, respectively, at 773 K and 33 kPa over the 30wt% H3PO4-modified cerium oxid

Non-Isothermal Kinetics and Mechanistic Study of Thermal Decomposition of Light Rare Earth Metal Nitrate Hydrates using Thermogravimetric Analysis

The formation of light rare earth metal oxides such as CeO2, La2O3, Sm2O3, Nd2O3 and Pr2O3 from thermal decomposition of its nitrate precursors (Ce(NO3)3·6H2O, La(NO3)3·6H2O, Sm(NO3)3·6H2O, Nd(NO3)3·6H2O and Pr(NO3)3·6H2O) have been investigated by thermogravimetric analysis. The rare earth metal oxides obtained were characterized for the nature of chemical bonds and textural properties using FTIR and N2-physisorption analyses, respectively. The FTIR analysis of the rare earth metal precursors and the oxides showed that the OH– and NO– bonds depicting the presence of hydrated water molecules and nitrate disappeared after the thermal decomposition leaving out only the pure solid oxides. The kinetics data obtained from the thermogravimetric analysis were fitted into “model free” kinetic expressions such as Kissinger, Ozawa–Flynn–Wall to calculate the apparent activation energy of the solid-state decomposition reaction of the rare earth metal precursors. The kinetic parameters were further analyzed using Coat–Redfern model to determine the possible mechanism of the decomposition process. The calculated values of the activation energy obtained from both Kissinger and Ozawa–Flynn–Wall models were similar compared to that obtained from Coat–Redfern model. Highest activation energies of 230.26, 344.78, 320.2.78, 392.72 and 258.26 kJ mol−1 were obtained from decomposition of Ce(NO3)3·6H2O, La(NO3)3·6H2O, Sm(NO3)3·6H2O, Nd(NO3)3·6H2O and Pr(NO3)3·6H2O), respectively, using Kissinger model, while the analysis of the kinetic data using Ozawa–Flynn–Wall model gave the highest activation energies of 229.01, 350.56, 348.56, 392.72 and 388.56 kJ mol−1 for decomposition of Ce(NO3)3·6H2O, La(NO3)3·6H2O, Sm(NO3)3·6H2O, Nd(NO3)3·6H2O and Pr(NO3)3·6H2O), respectively. Thirteen different models were evaluated using Coat–Redfern models in order to determine the mechanisms that govern the decomposition process. Interestingly, two-dimensional diffusion mechanism with activation energy of 105.61, 107.61, 140.61, 144.52 and 154.78 kJ mol−1 was obtained for thermal decomposition of Ce(NO3)3·6H2O, La(NO3)3·6H2O, Sm(NO3)3·6H2O, Nd(NO3)3·6H2O and Pr(NO3)3·6H2O), respectively. The rare earth metal oxides obtained from this study finds potential application as supports, promoters and catalysts in the field of catalysis