THE INDUSTRIAL MINERALOGY AND CATALYTIC INVESTIGATION OF ETHANOL OXIDATION BY DIFFERENT TYPES OF CRYPTOMELANE AND SOME RELEVANT COMPARATIVE MATERIALS

Catalysis is a $30 billion a year industry that involves several industrial minerals and is an area with large economic growth expected owing to energy, material and environmental demands. One material of emerging interest is cryptomelane, a potassium manganese oxide with a 2x2 octahedral molecular sieve structure. Although extensive catalytic research has been conducted on cryptomelanes produced by single synthesis methods little research has been done on cryptomelanes derived from multiple synthesis methods. For this investigation, multiple cryptomelane samples were synthesized using different techniques including aqueous route methods and a method using battery waste. These samples were then used in experiments to assess if they are effective catalysts for oxidation of ethanol – a volatile organic compound (VOC) used as an analog for other more environmentally damaging VOCs. For experiments 100 milligrams of cryptomelane samples, and comparative materials (electrolytic manganese dioxide and platinum catalyst) were placed in the middle of reaction tubes. The reaction tube was positioned in an oven and air flow is induced through the tube on one end with a diffusion tube filled with ethanol. A constant concentration of ethanol flows through the system passing through the catalyst in the reaction tube. The ethanol would then undergo catalysis transforming some ethanol to acetaldehyde and carbon dioxide. The ethanol and acetaldehyde were captured in a solution of water and isopropyl alcohol (IPA). The IPA is used to measure the relative concentrations of each alcohol using a gas chromatograph and carbon dioxide concentrations are measured using a KOH solution method.

The data collected from the gas chromatography data concluded that all the samples of cryptomelane and the EMD were in fact a catalyst however, effectiveness of each catalyst differed. Complete oxidation of ethanol by cryptomelane is typically achieved by 225°C and 50% conversion commonly occurs between 170 and 210 °C. EMD performs slightly better and Pt catalyst out performs all others. This work suggests cryptomelane and EMD may be of interest in catalytic applications if performance improvements can be made in the future.