Title : Innovative hydrocarbons recovery and utilization technology using reactor-separation membranes for off-gases emission
The increase in Greenhouse Gas (GHG) concentrations in the atmosphere as well as the depletion of hydrocarbon based fuels have become a global concern, as a result a number of methods aimed to recover and utilize GHG into valuable fuels and chemical feedstock are being developed. The major pollutants are carbon dioxide and methane that come from industrial processes and uncontrolled degradation of biomasses as well as inefficient processes of combustion respectively. This work incorporates the use of a y-type zeolite membrane on an alumina support to selectively permeate methane and carbon dioxide from inert gases and higher hydrocarbons and use the recovered gas as feed for methane dry reforming reaction using rhodium/alumina membrane incorporated into a shell and tube reactor. Characterisation of the modified membranes using nitrogen physisorption measurements showed the hysteresis isotherms of corresponding to type IV and V that is indicative of a mesoporous membrane. The surface areas and the pore size was determined using the Barrett, Joyner, Halenda (BJH) desorption method which showed the zeolite surface area to be 0.520 m2 g-1. Fourier Transform Infrared spectroscopy, Scanning Electron Microscope and Energy Dispersive X-ray Analysis confirmed the asymmetric deposition of rhodium, magnesium and zeolite crystals in the matrix of the alumina support. Single gas permeation tests showed that the synthesized y-type zeolite membrane at 293 K selectivity had a C3H8 /CH4 of 3.11 which is higher than the theoretical value of 0.60. Mixed gas permeation tests were carried out with the permeate and feed gases sent to the online GC equipped with a mass spectrometry detector (MS) and an automated 6-port gas sampling valve with a 30 mm Plot H column. The effect of feed pressure and temperature on the selectivity of the membrane was determined. The effect of gas temperature, feed flow rate and feed pressure on the conversion of the separated gas was studied. Increasing the reaction temperature from 1073 K to 1173 K showed an increase in conversion rate of 6.6 % while increasing the gas flow rate did not have a noticeable effect. The incorporation of magnesium oxide to the dispersed Rh/alumina membrane gave a conversion rate of 100 %.