Adsorption and diffusion of nitrogen, methane and carbon dioxide in aluminophosphate molecular sieve AlPO4-11

Vacuum pressure swing adsorption process for coalbed methane enrichment

Adsorption of carbon dioxide, ethane, and methane on titanosilicate type molecular sieves

A study of the pore size distribution for activated carbon monoliths and their relationship with the storage of methane and hydrogen

A compact adsorption-based process for removal of carbon dioxide and nitrogen from natural gas has been discussed. Among the adsorption-based processes, especially, the pressure swing adsorption (PSA) process has been a suitable unit operation for the purification and separation of gas because of low operation energy and cost. A step cycle is made up of pressurization, feed, equalization, blowdown and rinse. In this work, the PSA process is composed of zeolite 13X and carbon molecular sieve (CMS) for removal of carbon dioxide and nitrogen from mixed gas containing (75:21:4 vol%). A CMS selectively removes carbon dioxide and a zeolite 13X separates nitrogen from methane. CMS is investigated experimentally due to the high throughput of the faster diffusing component (). The gas composition of top, bottom and feed tank was measured with the gas chromatography (GC) using TCD detector, helium as carrier gas and packed column for analysis of methane, carbon dioxide, and nitrogen.

In order to reduce carbon dioxide emissions, pressure swing adsorption (PSA) process was studied to capture carbon dioxide from flue gas in a coal-fired power plant. Pressure swing adsorption features its low energy consumption, low investment, and simple operation. This study aims to capture carbon dioxide from flue gas by PSA process for at least 85 % CO2 purity and with the other stream of more than 90 % N2 purity. To validate the accuracy of the PSA simulation program, the extended Langmuir-Freundlich equation was adopted to fit measured equilibrium data to describe the adsorption equilibrium of adsorbent zeolite 13X. Next, the simulation study used the linear driving force model and compared the results of breakthrough curves and desorption curves between experiments and simulation to verify the accuracy of the mass transfer coefficient kLDF value in linear driving force model. The agreement between experimental data and the simulation results is good. Further, the simulation was verified with the 100-hour cyclic-steady-state experiment of the 3-bed 9-step PSA process studied. Flue gas after desulphurisation and water removal (13.5 % CO2, 86.5 % N2) of subcritical 1 kW coal-fired power plant was taken as feed to the designed 3-bed 9-step PSA process. To find the optimal operating conditions, the central composite design (CCD) was used. After analysis, optimal operating conditions were obtained to produce a bottom product at 89.20 % CO2 purity with 88.20 % recovery, and a top product at 98.49 % N2 purity with 93.56 % recovery. The mechanical energy consumption was estimated to be 1.17 – 1.41 GJ/t-CO2.

PSA Processes for Recovery of Carbon Dioxide

Gas adsorption separation of CO2/CH4 system using zeolite 5A

Hydrogen is an important energetic vector nowadays. The most common industrial method to produce ultrapure hydrogen is by steam methane reforming (SMR), where hydrogen is first produced as a mixture mainly composed of hydrogen, carbon monoxide, methane, and carbon dioxide. A purification step by pressure swing adsorption (PSA) is carried out usually using activated carbon and 5A zeolite as adsorbents. The design of this process requires fundamental information about the adsorption and diffusion of the components of SMR-off gas, which is only available in the literature for a limited number of adsorbents. In this work, adsorption Henry’s law constants and reciprocal diffusion time constants have been measured for hydrogen, carbon monoxide, methane, and carbon dioxide on BPL 4X10 activated carbon and 13X zeolite pellets from pulse experiments. Adsorption isotherms of these gases in both adsorbents at temperatures between 298 and 338 K, up to pressures of 20 bar for hydrogen and 2–5 bar for the other gases, have also been measured volumetrically. A PSA cycle for hydrogen purification using BPL activated carbon and 13X zeolite has been designed introducing the measured adsorption and diffusion data in a simulation tool. The process can yield 99.99+% hydrogen with 90% recovery and 7.2 mol H2 kg–1 h–1. If 13X zeolite is replaced by 5A zeolite with the same operating conditions, the hydrogen purity falls down to 99.81%.

The Pre-combustion IGCC Power Generation technology presents novel challenges in terms of gas turbine operation. The hydrogen-rich gaseous fuel has much higher heating value than conventional syngas. In a state of the art precombustion IGCC power plant, the fuel utilised in a gas turbine is generated on-site by a coal gasification unit followed by gas clean-up, water-gas (sour) shift reaction and CO2 sequestration. The Pressure Swing Adsorption (PSA) process is techno-economically promising option for separation of hydrogen from the syngas. However, the PSA process is inherently transient in nature. Performance of PSA process is dependent on the process configuration and various devised different PSA process configurations and reported the purity and recovery rate of hydrogen and carbon dioxide rich product gas streams. However, these process configurations published in literature are not directly adaptable to the state of the art pre-combustion IGCC power plant due to variations in the feed composition and condition. Moreover, the current research works have not addressed the impact of varying amount of hydrogen recovery on the power generation characteristics. Two important configurations of the PSA process are identified and their CAPEX is estimated.

Parallel and series multi-bed pressure swing adsorption processes for H2 recovery from a lean hydrogen mixture

ABSTRACTAdsorption isotherms data of methane and carbon dioxide gases on the activated carbons were measured experimentally using a volumetric method with pressure and temperatures ranging from 0 to 3.5 MPa and 27 to 65°C, respectively. Two types of activated carbons, namely, (1) Kalimantan Timur type activated carbon, which is lab-produced from Indonesian low-grade coal and (2) a commercial (Carbotech) activated carbon were used. The adsorption isotherms obtained were found to belong to type 1 of the International Union of Pure and Applied Chemistry classification. The adsorption uptakes for both carbon dioxide and methane on commercial activated carbon are higher than for the Kalimantan Timur activated carbon. This is due to higher Brunauer–Emmet–Teller surface area and pore volume of the former. Langmuir and Tóth isotherm models are correlated to predict the experimental data with acceptable accuracy.

Biocatalysis in polymer science

Kinetic separation of carbon dioxide from hydrocarbons using carbon molecular sieve

Assessment of the energy consumption of the biogas upgrading process with pressure swing adsorption using novel adsorbents

Adsorptive separations have gained considerable importance in process industry. A generic simulator has been developed in this work for Pressure Swing Adsorption (PSA) processes. Several simple and complex, conventional and unconventional PSA cycles have been studied using this simulator. Distinction has been made between PSA processes where a raffinate stream richer in the weakly adsorbed component as compared to the feed is the desired product as against processes where extract stream richer in the strongly adsorbed component is the desired product. These are termed as raffinate PSA and extract PSA respectively. Extract PSA is an unconventional process variation. The studies include several simple and complex PSA cycles for raffinate and extract PSA of industrial importance. The studies are aided by a generic simulator for all PSA process variations developed for the purpose. The simulator is equally applicable to Vacuum Swing Adsorption (VSA), Pressure Vacuum Swing Adsorption (PVSA), rapid cycle PSA processes, etc.