Ifeyinwa Orakwe

Study of the Selectivity of Methane over Carbon Dioxide Using CompositeInorganic Membranes for Natural Gas Processing

Natural gas is an important fuel gas that can be used as a power generation fuel and as a basic raw material in petrochemical industries. Its composition varies extensively from one gas field to another. Despite this variation in the composition from source to source, the major component of natural gas is methane with inert gases and carbon dioxide. Hence, all natural gas must undergo some treatment with about 20% of total reserves requiring extensive treatment before transportation via pipelines. The question is can mesoporous membrane be highly selective for methane and be used for the treatment of natural gas? A methodology based on the use of dip-coated silica and zeolite membrane was developed. A single gas permeation test using a membrane reactor was carried out at a temperature of 293 K and a pressure range of 1 × 10-5 to 1 × 10-4 Pa. The permeance of CH4 was in the range of 1.15 × 10-6 to 2.88 × 10-6 mols-1m-2Pa-1 and a CH4/CO2 selectivity of 1.27 at 293 K and 0.09 MPa was obtained. The pore size of the membrane was evaluated using nitrogen adsorption and was found to be 2.09 nm. The results obtained have shown that it is possible to use a mesoporous membrane to selectively remove carbon dioxide from methane to produce pipeline quality natural gas. There is a need for further study of the transport mechanism of methane through the membrane since this is essential for the separation of other hydrocarbons that could be present as impurities.

Membrane and Resins Permeation for Lactic Acid Feed Conversion Analysis

The process intensification of cellulose acetate membrane impregnation with resin catalysts and carrier gas transport with membrane was carried out. The different catalysts used were amberlyst 36, amberlyst 16, dowex 50w8x and amberlyst 15. The carrier gases used for the analysis of the esterification product were tested with a silica membrane before being employed for gas chromatography analysis. The different carrier gases tested were helium (He), nitrogen (N2), argon (Ar) and carbon dioxide (CO2). The experiments were carried out at the gauge pressure range of 0.10–1.00 bar at the temperature range of 25–100 °C. The carrier gas transport results with the membrane fitted well into the Minitab 2016 mathematical model confirming the suitability of Helium gas as a suitable carrier gas for the analysis of lactic acid feed with GC-MS. The esterification reaction of lactic acid and ethanol catalysed with the cellulose acetate membrane coupled with the different cation-exchange resins gave a conversion rate of up to 100%.

Characterization of an Alumina Membrane Using Single Gas Permeation

This paper discusses the results of initial experiments carried out using a commercially available alumina membrane. The paper also reveals the important features of ceramic membranes as well as the different transport mechanisms that could take place through these membranes. The experimental results were based on single gas permeation method involving He, O2, CO2 and N2. The effect of trans-membrane pressure drop, gas molecular mass, kinetic diameter, permselectivity, temperature and permeance were studied and discussed. Helium showed a faster flowrate through the membrane and the order of flow was He > O2 > N2 > CO2.

Characterization of Gamma-Alumina Ceramic Membrane

This paper presents the experimental results of different methods of characterization carried out on a gamma alumina ceramic membrane. A commercial gamma alumina mesoporous membrane has been used. The pore size, specific surface area and pore size distribution values were calculated with the use of a nitrogen adsorption-desorption instrument. The images from the scanning electron microscopy (SEM) showed the membranes’ morphological structure. Gas permeation tests were carried out on the membrane using a variety of single and mixed gases at a temperature range between 25–200 °C and gauge pressure range of 0.05–1 bar. Graphs of flow rate versus temperature were obtained. The results were therefore used to explain the effect of temperature on the flow rate of the various gases. At a pressure drop of 0.5 bar for example, the flow rate for N2 was relatively constant up to 150 °C before decreasing with further increase in temperature, while for O2, it continuously decreased with an increase in temperature.

Investigation of Flue Gas and Natural Gas Separation Using Silica Composite Membranes Formed on Porous Alumina Support

The overall goal of this paper is to foster the development of new membrane technologies to improve manufacturing efficiency and reduce CO2 emissions. Hence, a silica composite ceramic membrane with extremely low defect concentrations has been prepared through three successive dip-coating steps in a silica solution. An asymmetric structure was obtained by the deposition of silica layer on top of a combination of titanium and α-Al2O3 support. The morphology of the three step homogenous silica layer was analysed by scanning electron microscope and Energy dispersive x-ray analyzer. The transport property of the membranes was carried out at room temperature and at pressure differences ranging from 1 to 2 bar. The fabricated membrane has reproducible high permeance for CO2. Interestingly, an almost equal flow rate was observed for CH4 and N2 at a pressure of 2 bar. Separation factors obtained from CO2/CH4 and CO2/N2 are comparatively higher than Knudsen separation values.