A Novel Energy-Efficient Process for Production of Nitrogen from Air via a Reaction-Driven Membrane Reactor

Abstract

Gaseous nitrogen has a wide variety of applications in industry. Currently, nitrogen is produced by energyintensive cryogenic fractional distillation of liquefied air, pressure swing adsorption (PSA), and membranes. In this paper, a novel process was proposed and experimentally verified for production of nitrogen. In this process, oxygen in air is extracted through a dense oxygen−permeable membrane, which is then reacted with methane. By optimizing the air and methane flow rate, the process can produce nearly pure nitrogen as well as a syngas (a mixture of CO and H 2 ). At 800 °C, the reactor produced nitrogen at a rate of 9.2 mL cm −2 •min −1 with purity over 99%, and methane was reformed to syngas with CH 4 throughput conversion over 90%, H 2 selectivity of 92%, and CO selectivity of 92%. The syngas can be burned to generate heat or used as intermediate chemicals for production of liquid fuels and hydrogen. Since the membrane reactor is driven by the energy released by the reaction and does not consume high grade energy electricity, it has a much higher overall energy efficiency than the current industrial nitrogen separation processes.

Synthesis and gas transport properties of polyamide membranes containing PDMS groups

“…[4][5][6] Polymer membranes have been used in CO 2 recovery during oil recovery, oxygen and nitrogen separation from air, and natural gas sweetening. [7][8][9] Among them, polyamide (PA) is considered as excellent material for gas separation. [10][11][12] For example, Parthasarathi et al have evaluated the gas transport properties for PAs containing a uorinated biphenyl moiety.…”

A Review on the Application of Metal–Organic Frameworks (MOFs) in Pressure Swing Adsorption (PSA) Nitrogen Gas Generation

“…For N 2 generation via air separation, PSA systems are preferable for N 2 outlet purities above 95% and membranes more cost-effective below 95% purity N 2 gas. This is because of the air to N 2 ratio (air in/N 2 produced) being much better for PSA generation than membrane generation at higher outlet purities …”

“…For industrial processes requiring onsite N 2 gas generation, the processes used are either; cryogenic distillation of liquefied air or air separation using either PSA or membrane generation. 1 For very high-volume production, cryogenic distillation of liquid air is preferable, whereas air separation is preferred for low to medium volume requirements because of lower energy and cost requirements. 2 For N 2 generation via air separation, PSA systems are preferable for N 2 outlet purities above 95% and membranes more cost-effective below 95% purity N 2 gas.…”

“…This is because of the air to N 2 ratio (air in/N 2 produced) being much better for PSA generation than membrane generation at higher outlet purities. 1 Table 1 shows some example uses for low, medium, and high purity N 2 gas.…”