Pd based Inorganic Hollow Fibre Membranes for H2 Permeation and Methylcyclohexane Dehydrogenation

The availability of inorganic membranes which can withstand high temperatures and harsh chemical environments has resulted in a wide range of opportunities for the application of membranes in chemical reactions and separations. In particular, the combination of membrane separation and catalytic reaction into a single operating unit is an attractive way to increase conversions, improve yields and more efficient use of natural resources in many reactions. In this study, asymmetric alumina hollow fibres with different macrostructures consisting of finger-like macrovoids and a sponge-like packed pore structure in varying ratios have been prepared by a combined phase inversion/sintering technique. The asymmetric membranes in hollow fibre geometry possess superior surface area to volume ratios with less gas permeation resistance in comparison to commercial symmetric membranes in tubular and disk configurations. Such asymmetric hollow fibres are used as substrates onto which a Pd membrane is directly deposited by an electroless plating (ELP) technique without any pre-treatment of the substrate surface. A systematic study of the electroless plating of Pd and Ag onto an asymmetric alumina hollow fibre substrate has been carried out by direct measurement of one of the gaseous products, i.e. N2, using gas chromatography (GC). In addition, the influences of the substrate macrostructure on hydrogen permeation through the Pd/Al2O3 composite membranes have been investigated both experimentally and theoretically. Furthermore, a multifunctional Pd/alumina hollow fibre membrane reactor (HFMR) has been developed and employed for the catalytic dehydrogenation of methylcyclohexane (MCH) to toluene (TOL). The developed HFMR consists of a thin and defect-free Pd membrane coated directly onto the outer surface of an asymmetric alumina hollow fibre substrate. 50 wt% Ni/Al2O3 nano-sized catalysts were directly impregnated into the substrate. The performance of HFMR has also been compared with several different reactor configurations

A catalytic hollow fibre membrane reactor for combined steam methane reforming and water gas shift reaction

A catalytic hollow fibre membrane reactor (CHFMR) was developed in this study for combined steam methane reforming (SMR) and water gas shift (WGS) reaction. This is achieved by incorporating a Ni/SBA-15 catalyst into a plurality of micro-channels with open entrance from inner surface of Al2O3 hollow fibres, followed by coating of a 3.3μm Pd membrane on the outer surface of the hollow fibre using an electroless plating method. In addition to systematic characterizations of each reactor component, i.e. Ni/SBA-15 catalyst, micro-structured ceramic hollow fibre and Pd separating layer, the effect of how the reactor was assembled or fabricated on the catalytic performance was evaluated. Electroless plating of the Pd membrane impaired the catalytic performance of the deposited Ni/SBA-15 catalyst. Also, the over-removal of hydrogen from the reaction zone was considered as the main reason for the deactivation of the Ni-based catalyst. Instead of mitigating such deactivation using "compensating" hydrogen, starting the reaction at higher temperatures was found more efficient in improving the reactor performance, due to a better match between hydrogen production (from the reaction) and hydrogen removal (from the Pd membrane). An effective methane conversion of approximately 53%, a CO2 selectivity of 94% and a H2 recovery of 43% can be achieved at 560°C. In order for a more significant "shift" phenomenon, alternative methodology of fabricating the reactor and more coke resistant catalysts are recommended

Pd based inorganic hollow fibre membranes for H2 permeation and methylcyclohexane dehydrogenation

The availability of inorganic membranes which can withstand high temperatures and harsh chemical environments has resulted in a wide range of opportunities for the application of membranes in chemical reactions and separations. In particular, the combination of membrane separation and catalytic reaction into a single operating unit is an attractive way to increase conversions, improve yields and more efficient use of natural resources in many reactions. In this study, asymmetric alumina hollow fibres with different macrostructures consisting of finger-like macrovoids and a sponge-like packed pore structure in varying ratios have been prepared by a combined phase inversion/sintering technique. The asymmetric membranes in hollow fibre geometry possess superior surface area to volume ratios with less gas permeation resistance in comparison to commercial symmetric membranes in tubular and disk configurations. Such asymmetric hollow fibres are used as substrates onto which a Pd membrane is directly deposited by an electroless plating (ELP) technique without any pre-treatment of the substrate surface. A systematic study of the electroless plating of Pd and Ag onto an asymmetric alumina hollow fibre substrate has been carried out by direct measurement of one of the gaseous products, i.e. N2, using gas chromatography (GC). In addition, the influences of the substrate macrostructure on hydrogen permeation through the Pd/Al2O3 composite membranes have been investigated both experimentally and theoretically. Furthermore, a multifunctional Pd/alumina hollow fibre membrane reactor (HFMR) has been developed and employed for the catalytic dehydrogenation of methylcyclohexane (MCH) to toluene (TOL). The developed HFMR consists of a thin and defect-free Pd membrane coated directly onto the outer surface of an asymmetric alumina hollow fibre substrate. 50 wt% Ni/Al2O3 nano-sized catalysts were directly impregnated into the substrate. The performance of HFMR has also been compared with several different reactor configurations.EThOS - Electronic Theses Online ServiceMinistry of Higher Education of Malaysia (MOHE), and University Malaysia Perlis (UniMAP)GBUnited Kingdo

Pd based inorganic hollow fibre membranes for H2 permeation and methylcyclohexane dehydrogenation

The availability of inorganic membranes which can withstand high temperatures and harsh chemical environments has resulted in a wide range of opportunities for the application of membranes in chemical reactions and separations. In particular, the combination of membrane separation and catalytic reaction into a single operating unit is an attractive way to increase conversions, improve yields and more efficient use of natural resources in many reactions. In this study, asymmetric alumina hollow fibres with different macrostructures consisting of finger-like macrovoids and a sponge-like packed pore structure in varying ratios have been prepared by a combined phase inversion/sintering technique. The asymmetric membranes in hollow fibre geometry possess superior surface area to volume ratios with less gas permeation resistance in comparison to commercial symmetric membranes in tubular and disk configurations. Such asymmetric hollow fibres are used as substrates onto which a Pd membrane is directly deposited by an electroless plating (ELP) technique without any pre-treatment of the substrate surface. A systematic study of the electroless plating of Pd and Ag onto an asymmetric alumina hollow fibre substrate has been carried out by direct measurement of one of the gaseous products, i.e. N2, using gas chromatography (GC). In addition, the influences of the substrate macrostructure on hydrogen permeation through the Pd/Al2O3 composite membranes have been investigated both experimentally and theoretically. Furthermore, a multifunctional Pd/alumina hollow fibre membrane reactor (HFMR) has been developed and employed for the catalytic dehydrogenation of methylcyclohexane (MCH) to toluene (TOL). The developed HFMR consists of a thin and defect-free Pd membrane coated directly onto the outer surface of an asymmetric alumina hollow fibre substrate. 50 wt% Ni/Al2O3 nano-sized catalysts were directly impregnated into the substrate. The performance of HFMR has also been compared with several different reactor configurations.EThOS - Electronic Theses Online ServiceMinistry of Higher Education of Malaysia (MOHE), and University Malaysia Perlis (UniMAP)GBUnited Kingdo

Purification of bioactive phenolics from Phanerochaete chysosporium biomass extract on selected macroporous resins

In this study, two different types of macroporous resins known as XAD-7HP and HP-20 were evaluated for the adsorption and desorption properties against bioactive phenolics extracted from Phanerochaete chrysosporium. For static sorption, the study were conducted at different phase contact time, solution pH and ethanol concentration by static adsorption/ desorption method. From the results, it was found that the adsorption capacity for both resins had has no significant difference. Then, the kinetic adsorption data were analyzed with both pseudo-first-order and pseudo-second-order equations and the later performed better. The adsorption isotherm data were fitted well by both Langmuir and Freundlich models. Meanwhile in desorption study, HP-20 and XAD-7HP gave 90.52% and 88.28% recoveries, respectively. Considering the desorption results of the macroporous resins, HP-20 and XAD-7HP were packed in chromatography column to further purify the phenolics. For dynamic adsorption, breakthrough capacity of HP-20 (0.522) was found to be higher than XAD7HP (0.131). Different ethanol concentrations (30% to 50% (v/v)) were investigated at fixed flowrate (1 ml/min) on phenolics recovery from both types of resins. The highest recovery of bioactive phenolics was 94.3% using XAD-7HP resins at 50% (v/v) of ethanol. Only 77.1% of bioactive phenolics were recovered using HP-20 resin at the same experimental conditions. The purified extract subsequently was analyzed using HPLC. The results showed that three phenolics (gallic acid 3,4-dihydroxybenzoic acid and 4-hydroxybenzoic acid) were identified with higher concentrations as compared to non-purified extract. Finally, the purified extract was tested for scavenging activity against DPPH, and it showed that the activity increased significantly to 90.80% from 59.94% in non-purified extract

Adsorption and desorption kinetic studies of bioactive phenolics purification on selected macroporous resins

In this study, two different types of macroporous resins known as XAD-7HP and HP-20 were evaluated for the adsorption and desorption properties against bioactive phenolics extracted from Phanerochaete chrysosporium. The study was conducted at different phase contact time, solution pH and ethanol concentration by static adsorption and desorption methods. From the results, it was found that the adsorption capacity for both resins has no significant difference. Meanwhile in desorption study, HP-20 and XAD-7HP gave 90.52% and 88.28% recoveries, respectively. Then, the kinetic adsorption data were analyzed with both pseudo-first-order and pseudo-second-order equations and the later performed better. The adsorption isotherm data were fitted well by both Langmuir and Freundlich models

Batch adsorption and desorption kinetic studies of bioactive phenolics on selected macroporous resins

In this study, two different types of macroporous resins known as XAD-7HP and HP-20 were evaluated for the adsorption and desorption properties against bioactive phenolics extracted from Phanerochaete chrysosporium. The study was conducted at different phase contact time, solution pH and ethanol concentration by static adsorption and desorption methods. From the results, it was found that the adsorption capacity for both resins has no significant difference.Meanwhile in desorption study, HP-20 and XAD-7HP gave 90.52% and 88.28% recoveries, respectively. Then, the kinetic adsorption data were analyzed with both pseudo-first-order and pseudo-second-order equations and the later performed better. The adsorption isotherm data were fitted well by both Langmuir and Freundlich models

Dye removal from aqueous solution by using adsorption on treated sugarcane bagasse

The use of cheap and ecofriendly adsorbents has been studied as an alternative substitution of activated carbon for the removal dyes from wastewater. Adsorbents prepared from sugarcane baggase-an agro industries waste was successfully used to remove the methyl red from an aqueous solution in a batch reactor. This study investigates the potential use of sugarcane baggase, pretreated with formaldehyde (PCSB) and sulphuric acid (PCSBC), for the removal of methyl red from simulated wastewater. Formaldehyde treated and sulphuric acid treated sugarcane bagasse were used to adsorb methyl red at varying dye concentration, adsorbent dosage, pH and contact time. Similar experiment was conducted with commercially available powdered activated carbon (PAC), in order to evaluate the performance of PCSB and PCSBC. The adsorption efficiency of different adsorbents was in the order PAC>PCSBC>PCSB. The initial pH of 6-10 flavors the adsorption of both PCSB and PCSBC. Adsorbents are very efficient in decolorized diluted solution. It is proposed that PCSB and PCSBC, in a batch or stirred tank reactors could be employed as a low cost alternative in wastewater treatment for the dye removal