Innovative hydrocarbons recovery and utilization technology using reactor-separation membranes for off-gases emission during crude oil shuttle tanker transportation and natural gas processing.

The increase in greenhouse gas (GHG) concentrations in the atmosphere, as well as the high rate of depletion of hydrocarbon-based resources have become a global concern. A major source of emissions of hydrocarbon vapours occur during loading and offloading operations in crude oil shuttle tanker transportation. The emitted gases have a typical composition of 60 % N2, 10 % CO2, 5% O2, 5 % C3H8, 10% CH4, 5% C2H6 and 5 % higher hydrocarbons. As a result, various methods aimed to add value to GHG to produce valuable fuels and chemical feedstock are being developed. This work incorporates the use of silica, polyurethane/zeolite and y-type zeolite membrane on an alumina support to selectively permeate methane and carbon dioxide from inert gases and higher hydrocarbons. The recovered gas is upgraded by dry reforming reactions employing rhodium/alumina membrane incorporated into a shell and tube reactor. Mixed gas permeation tests have been carried out with the permeate and feed gases sent to the online gas chromatograph (GC) equipped with a mass spectrometry (MS) detector and an automated 6-port gas sampling valve with a 30 mm HP- Plot Q column. The question is what mesoporous membrane can be highly selective for the separation of methane and carbon dioxide from inert gases and higher hydrocarbons, and what is the effect of temperature and feed gas pressure on the conversion of separated gases? Characterisation of the modified membranes was carried out using nitrogen physisorption measurements and showed the hysteresis isotherms corresponding to type IV and V, which is indicative of a mesoporous membrane. The surface area and the pore size were determined using the Barrett, Joyner, Halenda (BJH) desorption method, which showed the silica membrane had a larger surface area (10.69 m2 g-1) compared to zeolite (0.11 m2 g-1) and polyurethane/zeolite membrane (0.31 m2 g-1). Fourier Transform Infrared spectroscopy, Scanning Electron Microscope and Energy Dispersive X-ray Analysis confirmed the asymmetric deposition of silica, polyurethane, rhodium and zeolite crystals in the matrix of the alumina support. Single gas permeation tests showed that the synthesised y-type zeolite membrane at 293 K had a CH4/C3H8 selectivity of 3.11, which is higher than the theoretical value of 1.65. The permeating CH4 and C3H8 flux at 373 K and a pressure of 1 x 105 Pa was 0.31 and 0.11 mol s-1 m-2 respectively proving that zeolite has molecular sieving mechanism for separation of methane and propane. The silica membrane exhibited higher effectiveness for the separation of CO2 than the other membranes. For methane dry reforming using a supported rhodium membrane, an increase of the reaction temperature from 973 K to 1173 K showed an increase in conversion rate of CO2 and CH4 from less than 20% to over 90% while increasing the gas hourly space velocity (GHSV) did not have a noticeable effect. The study revealed the high potential of the zeolite and rhodium membrane for gas separation and dry reforming reactions concept in creating value-added carbon-based products from CO2 and CH4

Gas transport and characterization of inorganic ceramic membrane for lactic acid esterification.

Ethyl lactate is an important organic ester, which is biodegradable in nature and widely used as food additive, perfumery, flavor chemicals and solvent. Inorganic porous ceramic membrane has shown a lot of advantages in the equilibrium process of ethyl lactate separation. In this work, the transport characteristic of carrier gas including Nitrogen (N2), Helium (He), Argon (Ar) and Carbondioxide (CO2), with α-Al2O3 inorganic ceramic membrane used for ethyl lactate separation was investigated, at the pressure drop of 0.01-0.09bar and 298K. The carrier gas flow rate was molecular weight dependent in the order: He > Ar > N2 > CO2 with respect to pressure drop. The membrane pore size distribution was analysed using Scanning electron microscope coupled with energy dispersive x-ray analyser (SEM-EDXA). THIS PAPER WON CERTIFICATE OF MERIT(STUDENT) FOR INTERNATIONAL CONFERENCE ON CHEMICAL ENGINEERING 2014: MISS EDIDIONG OKO

Characterisation of inorganic composite ceramic membrane for lactic acid esterification processes.

The use of inorganic composite membranes in chemical industries has received a lot of attention more recently due to a number of exceptional advantages, including thermal stability and robustness. Inorganic membranes can selectively remove water from the reaction mixture during esterification reactions in order to enhance product formation. The characterisation of inorganic composite membranes used in this work including the determination of the pore diameter and specific surface area was performed using liquid nitrogen adsorption at 77 K. The membrane was modified once. The permeation test for the single gases including carbon dioxide (CO2), helium (He), nitrogen (N2) and argon (Ar) through the inorganic composite ceramic membrane was carried out at the gauge pressure range of 0.10-1.00 bar and at the temperature of 393 K. The order of the gas molecular weight was He < N2 < CO2 < Ar. The BET surface area of the dip-coated silica membrane showed a type IV isotherm characteristic of mesoporous structure with hysteresis. The BJH curve of the silica-membrane was in accordance with mesoporous classification

Transport in catalytically active porous membrane application in seawater deoxygenation for pressure maintenance.

In this study, inorganic tubular ceramic membranes with highly-dispersed catalytic metal: palladium and platinum were produced on both meso and macro-porous membranes. The membranes were characterised by energy dispersive x-rays (EDAX), scanning electron microscopy (SEM), BET liquid nitrogen adsorption and hydrogen gas transport behaviour. They were tested for sea water deoxygenation by feeding seawater saturated with hydrogen under various operating conditions and monitoring the downstream oxygen removal rate. The results far exceeded those of a traditional fixed be catalytic reactor

The use of nano-composite ceramic membranes for gas separations.

The preparation of composite ceramic inorganic membranes using different types of support with the aim to achieving high selectivity for lower hydrocarbons was studied. The pore size of the unmodified support was determined. Upon modification of the support, the morphology was examined using scanning electron microscopy (SEM), which showed a reduction in the pore radius and pore size inorganic ceramic membrane consisting of a ceramic support and a zeolite layer. The permeance of nitrogen, carbon dioxide, helium, methane, propane and argon through the membrane at varying pressures was determined. The effect of the mean pressure of up to 0.1 MPa on the molar flux of the gases at 294K was determined

Preparation and characterization of palladium ceramic alumina membrane for hydrogen permeation.

In this study, a tubular palladium membrane has been prepared by an electroless plating method using palladium II chloride as a precursor with the intent of not having a completely dense film since its application does not require high hydrogen selectivity. The support used was a 15 nm pore sized tubular ceramic alumina material that comprised of 77% alumina and 33% titania. It has dimensions of 7 mm inner and 10 mm outer diameters respectively. The catalyst was deposited on the outside tube surface using the electroless deposition process. The membrane was morphologically characterized using scanning electron microscopy/energy dispersive x-ray analysis (SEM/EDXA) and liquid nitrogen adsorption/desorption analysis (BET) to study the shape and nature of the palladium plating on the membrane. The catalytic membrane was then inserted into a tubular stainless-steel holder which was wrapped in heating tapes so as to enable the heating of the membrane in the reactor. The gases used for permeation tests comprised H2, N2, O2 and He. Permeation tests were out at 573 K and at pressure range between 0.05 and 1 barg. The results showed that hydrogen displayed a higher permeation when compared to other gases that permeated through the membrane and its diffusion is also thought to include solution diffusion through the dense portions of the palladium in addition to Knudsen, convective and molecular sieving mechanisms occurring through cracks and voids along the grain boundaries. While high hydrogen selectivity is critically important in connection with hydrogen purification for fuel cells and in catalytic membrane reactors used to increase the yield of thermodynamically limited reactions such as methane steam reforming and water–gas shift reactions whereby the effective and selective removal of the H2 produced from the reaction zone shifts the equilibrium, it is not so important in situations in which the membrane has catalytic activity such that it is possible to carryout the reaction in situations where the premixed reactants are forced-through the membrane on which the catalysts is attached. This type of catalytically active membranes is novel and has not been tested in gas-solid-liquid reactions and liquid-solid reactions before. With such a reactor configuration, it is possible to achieve good feed stream distribution and an optimal usage of the catalytic material. The preparation and characterization of such membrane catalysts has gained increased interest in the process industries because it can be adapted to carryout the chemical reactions if one of the reactants is present in low concentration and an optimal reactant distribution results in a better utilization of the active catalytic material. However, there are concerns in terms of the high cost of palladium membranes and research on how to fabricate membranes with a very low content of the palladium catalyst is still ongoing. Work is currently underway to deploy the Pd/Al2O3 membrane catalysts for the deoxygenating of water for downhole injection for pressure maintenance and in process applications

Utilization of CO2 for syngas production by CH4 partial oxidation using a catalytic membrane reactor.

In this research, a synthetic flue gas mixture with added methane was used as the feed gas in the process of dry reforming with partial oxidation of methane using a laboratory scale catalytic membrane reactor to produce hydrogen and carbon monoxide that can present the starting point for methanol or ammonia synthesis and Fischer-Tropsch reactions. 0.5% wt% Rh catalyst was deposited on a γ-alumina support using rhodium (III) chloride precursor and incorporated into a shell and tube membrane reactor to measure the yield of synthesis gas (CO and H2) and conversion of CH4, O2 and CO2 respectively. These measurements were used to determine the reaction order and rate of CO2. The conversion of CO2 and CH4 were determined at different gas hourly space velocities. The reaction order was determined to be a first-order with respect to CO2. The rate of reaction for CO2 was found to follow an Arrhenius equation having an activation energy of 49.88 × 10−1 kJ mol−1. Experiments were conducted at 2.5, 5 and 8 ml h−1 g−1 gas hourly space velocities and it was observed that increasing the hourly gas velocities resulted in a higher CO2 and CH4 conversions while O2 conversion remained fairly constant. CO2 had a high conversion rate of 96% at 8 ml h−1 g−1. The synthesized catalytic membrane was characterized by Scanning Electron Microscopy (SEM) and the Energy Dispersive X-ray Analysis (EDXA) respectively. The micrographs showed the Rh particles deposited on the alumina support. Single gas permeation of CH4, CO2 and H2 through the alumina support showed that the permeance of H2 increased as the pressure was increased to 1 × 105 Pa. The order of gas permeance was H2 (2.00 g/mol) > CH4 (16.04 g/mol) > N2 (28.01 g/mol) > O2 (32 g/mol) > CO2 (44.00 g/mol) which is indicative of Knudsen flow mechanism. The novelty of the work lies in the combination of exothermic partial oxidation and endothermic CO2 and steam reforming in a single step in the membrane reactor to achieve near thermoneutrality while simultaneously consuming almost all the greenhouse gases in the feed gas stream

A comparative evaluation of the hydrogen separation, purification and transport behavior of α-alumina membrane and γ-alumina membranes modified with ALOOH sol.

The main purpose of this work is to investigate the hydrogen permeation behavior of a commercial ceramic alumina membrane and compare same with that of a γ-alumina membrane graded with an AlOOH sol using the dip coating method. The permeance of hydrogen and 5 other single gases (He, N2, CH4, CO2 and Ar) were investigated at high temperatures. Mixed gas permeation tests for a H2 gas mixture were also carried out. Results showed that the permeance of H2 increased with increasing temperature for the graded γ- Al2O3 membrane while it decreased for the α-Al2O3 support. For the single gas tests, the α-Al2O3 support show higher permeance of up to 9.45 x 10-3 mol m-2 s-1 Pa -1 compared to 1.03 x 10-3 mol m-2 s-1 Pa-1 for the γ-Al2O3 but the graded substrate was permeable to only H2 at fifth coating. The mixed gas tests for a gas mixture (H2= 50%, CO= 28%, CO2=10% CH4=8%, N2=4%) show lower H2 permeance which was attributed to the inhibition effect of CO2 in the gas mixture. The H2/N2 permselectivity for both membranes was close to the theoretical Knudsen value of 3.73 which suggests a combined viscous and Knudsen flow transport mechanism

Novel zeolite-polyurethane membrane for environmental applications and gas separations.

This research work investigates the effect of polyurethane polymer on the separation of CO2, CH4 and C3H8 through a zeolite/polyurethane mixed matrix membrane. A methodology based on the modification of porous ceramic inorganic support with the aim to achieve high selectivity for the hydrocarbons has been developed. Polyurethane-zeolite nanoparticles were prepared by combined blending and casting method. The physical properties of the zeolite/polyurethane mixed matrix membrane were investigated by Scanning Electron Microscope (SEM), Fourier Transform Infra-Red spectroscopy (FTIR) and Nitrogen physisorption (BET). These confirmed the homogenous and nanoscale distribution of zeolite particles in the polyurethane-zeolite membrane. The Nitrogen physisorption measurements showed the hysteresis isotherm of the membrane corresponding to type IV and V that is indicative of a mesoporous membrane. The surface area and the pore size determined using the Barrett, Joyner, Halenda (BJH) desorption method showed a pore diameter of 3.320 nm, a pore volume of 0.31ccg-1 and surface area of 43.583 m2 g-1. Single gas permeation tests were carried out at a pressure range of 0.01 to 0.1 MPa. The membrane showed the permeance of CH4 to be in the range of 5.189 × 10-7 to 1.78 × 10-5 mol s-1 m-2 Pa-1 and a CH4/C3H8 selectivity of 3.5 at 293 K. On the basis of the results obtained it can be concluded that for the recovery of volatile organic compounds the addition of polyurethane polymer to the zeolite membrane did not increase the performance of the membrane

Predicting multicomponent gas transport in hybrid inorganic membranes.

A repeated dip-coating technique has been used to prepare novel inorganic multilayered membranes. The membranes have been characterizated by Scanning Electron Microscopy (SEM) and nitrogen adsorption (ASAP 2010) respectively. The three-parameter model incorporating the gas transport characteristics of the hybrid membranes has been adequately described using a combination of Knudsen and Viscous flows. The model has been used to predict gas transport rates through the membranes over a wide range of gas compositions and good agreement has been observed with experimental data. The model has also been applied to estimate the separation layer thickness. The estimated value of 1.6m is in good agreement with that of 1.62m observed by scanning electron microscopy. The gases studied include O2, N2, He, H2 and mixtures of CO2/N2 and O2/N2, respectively. All experiments were carried out at room temperature and were found to possess both Knudsen and viscous flow as predicted by the model