Erhan Deniz

High capacity carbon dioxide adsorption by inexpensive covalent organic polymers

Efficient CO2 scrubbing without a significant energy penalty remains an outstanding challenge for the fossil fuel-burning industry where aqueous amine solutions are still widely used. Porous materials have long been evaluated for next generation CO2 adsorbents. Porous polymers, robust and inexpensive, show promise as feasible materials for the capture of CO2 from warm exhaust fumes. We report the syntheses of porous covalent organic polymers (COPs) with CO2 adsorption capacities of up to 5616 mg g−1 (measured at high pressures, i.e. 200 bar) and industrially relevant temperatures (as warm as 65 °C). COPs are stable in boiling water for at least one week and near infinite CO2/H2 selectivity is observed.

Amidoximes: promising candidates for CO2 capture

Monoethanolamine (MEA) dominates power plant carbon dioxide (CO2) scrubbing processes, though with major disadvantages such as a 8–35% energy penalty. Here we report that structurally comparable amidoximes are promising CO2 capture agents based on RIMP2 electronic structure calculations. This was experimentally verified by the synthesis and testing of representative amidoximes for capture efficiencies at pressures as high as 180 bar. Acetamidoxime, which has the highest percent amidoxime functionality showed the highest CO2 capacity (2.71 mmol g−1) when compared to terephthalamidoxime (two amidoximes per molecule) and tetraquinoamidoxime (four amidoximes per molecule). Polyamidoxime surpassed activated charcoal Norit RB3 for CO2 capture per unit surface area. Adsorption isotherms exhibit Type IV behavior and acetamidoxime found to increase CO2 capture with temperature, a less observed anomaly. Porous amidoximes are proposed as valuable alternatives to MEA.

Synthesis, characterization and evaluation of porous polybenzimidazole materials for CO2 adsorption at high pressures

Porous polybenzimidazole polymers have been under investigation for high and low pressure CO2 adsorption due to the well-built stability under high pressure and at various temperatures. Pressure swing and temperature swing processes like integrated gasification combined cycle require materials which can operate efficiently at high pressure and high temperature and can remove CO2. In this manuscript we report synthesis, characterization and evaluation of two polybenzimidazole materials (PBI-1 and PBI-2), which were prepared with two different solvents and different cross-linking agents by condensation techniques. Low and high pressure CO2 sorption characteristic of both the materials were evaluated at 273 and 298xa0K. Thermal gravimetric analysis showed high temperature stability up to 500xa0°C for the studied materials. PBI-1 has shown very good performance by adsorbing 3 times more (1.8025xa0mmolg−1 of CO2) than PBI-2 at 0xa0°C and at low pressures. Despite low surface area results obtained via BET techniques, at 50 bars PBI-1 adsorbed up to 6.08xa0mmolg−1 of CO2. Studied materials have shown flexible behavior under applied pressure that leads to so-called “gate-opening” adsorption behavior and it makes these materials promising adsorbents of CO2 at high pressures and it is discussed in the manuscript in detail.

Natural Gas Hydrates

Sir Humphry Davy witnessed the first chlorine hydrate crystallizing in 1811. Couple of century later his discovery, natural gas hydrates has begun to play an important role in energy business. From being a mere chemical curiosity, they have proven to be a nuisance for the natural gas industry. The problem of hydrate induced blockage in “wet gas” flow systems has been widely reported and became a major flow assurance issue in the energy sector[1]. The importance of pipeline blockage increased in the 70’s when plugging of even the largest diameter pipelines from offshore, arctic fields or the wells from high-pressure underground storage facilities were reported. Studies over the past two decades showed that large gas hydrate plugs form most often after shut-in pipelines or wells begin to flow[2]. When a pipeline is shut-in, the fluid separates into the gas water and hydrocarbons as the temperature decreases[3].