ABSTRACT

This chapter attempts to compare membranes in relationship to more established technologies for commercial gas separation. For each separation technology, a number of process options are possible, representing different trade-offs between power, capital, and product recovery. The chapter focuses on air and hydrogen separations – the two areas where gas separation membranes have made the most impact. The key features of the various technologies, such as power consumption, capital cost, product purity, and recovery, are addressed. The critical factors for various applications, such as purity, utilization patterns, flow rates, and use pressures that could govern the selection of the process will be highlighted. The impact of future developments, with particular emphasis on the improvements in membrane technology to gain wider acceptance in commercial gas separation is discussed. The differences in strength of interaction between a solid surface and the different gas molecules in a mixture can provide the basis for adsorptive separation.