Context and Background
At present, hydrogen is gaining more recognition as a means to transport energy, due to the increased implementation of fuel cells, among other reasons. For instance, oil refineries have expressed the need to improve and increase the number of hydrotreating processes for sulfur removal in fuels. Another important issue is the reduction of impurities in hydrogen for its further use, as some processes require purity as high as 99.99% (Xiao, Fang, Bénard, and Chahine, 2018). It should be noted that the availability of hydrogen from natural sources does not match the demands of the industry, which is why its industrial production is so critical.
Commercially, a number of adsorption processes have been developed, including such widely used options as pressure swing adsorption (PSA), vacuum pressure swing adsorption (VPSA), and thermal or temperature swing adsorption (TSA) (Hauchhum & Mahanta, 2014).
Hauchhum and Mahanta (2014) show that the aforementioned processes have been tested for efficiency in a number of studies, and the evidence has shown that PSA promises decent perspectives in the field. Among the advantages of the approach is its convenience of implementation over a broad range of temperature and pressure conditions, as well as cost-efficiency and low energy requirements. The first stage of adsorption process design includes selecting an appropriate adsorbent with necessary selectivity and working capacity (Wynnyk, Hojjati, Pirzadeh & Marriott, 2017). As of now, the industry uses a wide variety of adsorbents: activated carbon, zeolites, silica gel, activated alumina, urea-formaldehyde, and others.
Problem Statement and Potential Benefits
In recent years, hydrogen storage has received a great deal of traction as a topic of research because of growing concerns over the use of fossil fuels. Even though the industrial applications of the PSA processes for hydrogen separation are becoming more ubiquitous, the development and optimization of commercial units still require an empirical approach. Delgado et al. (2014) write that any experimental effort in this field would require adsorption equilibrium data as well as adsorption kinetics data. To date, only limited research has been carried out with regards to investigating the properties of microporous materials such as zeolites, even though their practical use is well-established (Langmi et al., 2003).
Therefore, it is critical to explore the potential of zeolites for separating hydrogen from syngas in PSA further. If successful, the findings will contribute to the growing body of research on environmentally sound solutions in fossil use.
Research Challenges and Possible Approaches
Delgado et al. (2014) report that research in the selected field is challenged due to the scarcity of fundamental studies about the adsorption of the essential components of syngases. Langmi et al. (2003) propose an experimental approach in which several types of zeolites of varying pore geometries and compositions are contrasted against each other. First, they are synthesized through hydrothermal methods; their various cation-exchanged forms are achieved through ion exchange from aqueous metal nitrate solutions. Langmi et al. (2003) measured hydrogen adsorption capacities by applying a constant pressure thermogravimetric analyzer over a variety of pressures from 0 to 15 bar and temperatures from -196 to 300C. Powder X-ray diffraction is used to explore the phase composition and crystallinity of zeolite samples.
Desirable Outcomes and Deliverables
The desirable outcome for the present study is the objective measurement of hydrogen uptake in zeolites that would be meaningful for the industry and have practical implications. Some of the key deliverables for the project are the identification of the dependence of hydrogen uptake in zeolites on such factors as temperature, framework, and cation type. The data shall serve in predicting breakthrough curves and performance of PSA processes in the hydrogen separation.
Reference List
Delgado, JA, Águeda, VI, Uguina, MA, Sotelo, JL, Brea, P and Grande, CA 2014, Adsorption and diffusion of H2, CO, CH4, and CO2 in BPL activated carbon and 13X zeolite: evaluation of performance in pressure swing adsorption hydrogen purification by simulation. Industrial & Engineering Chemistry Research, 53(40), pp. 15414-15426.
Hauchhum, L and Mahanta, P 2014, Carbon dioxide adsorption on zeolites and activated carbon by pressure swing adsorption in a fixed bed. International Journal of Energy and Environmental Engineering, 5(4), pp. 349-356.
Langmi, HW et al. 2003, Hydrogen adsorption in zeolites A, X, Y and RHO. Journal of Alloys and Compounds, 356, pp. 710-715.
Wynnyk, KG, Hojjati, B, Pirzadeh, P and Marriott, RA 2017, High-pressure sour gas adsorption on zeolite 4A. Adsorption, 23(1), pp. 149-162.
Xiao, J, Fang, L, Bénard, P and Chahine, R 2018, Parametric study of pressure swing adsorption cycle for hydrogen purification using Cu-BTC. International Journal of Hydrogen Energy, 43(30), pp. 13962-13974.