Synthesis of Micro/Mesoporous Composites and Their Application as CO₂ Adsorbents

Abstract

We synthesized a series of micro/mesoporous composites of S-β-MCM41(c), P-β-MCM41(c), P-ZSM-MCM41(c), P-ZSM-C through a two-step crystallization process. During this process, the microporous zeolite precursor solution (S) or the zeolite powder (P) was first synthesized and treated with NaOH solution with different concentration (c), and then the mesopores were induced by hexadecyltrimethylammoniumbromide (CTAB) as a soft template or mesoporous carbon as a hard template. The effects of the type of inorganic precursor, the base concentration, and the type of mesoporous template on the structure and property of the micro/mesoporous composites were investigated. The results of X-ray diffraction (XRD), transmission electron microscopy (TEM), and nitrogen adsorption-desorption isotherms showed that the products contained micropores and mesopores, simultaneously. The CO2 adsorption capacities of these micro/mesoporous composites were obviously improved compared to the pure microporous or mesoporous materials. Among them, P-ZSM-MCM41(2) had the highest CO2 adsorption capacity of 1.51 mmol •g -1 , which was almost twice that of the original ZSM-5.

Synergy effects of Mo2C and AC on the structure and catalytic performance of Mo2C/AC for NO2 to NO

“…On one hand, Mo species particles will block some of the pores; on the other hand, AC provides a carbon source for molybdenum carbide during carburization, and its microporous structure is damaged to a certain extent. 21 The decrease in the pore volume of the micropores may be due to the fact that Mo species are mainly distributed in the micropores. 18,22 With the increase of w(Mo), the specific surface area, total pore volume, and micropore pore volume all decrease, probably because more C atoms are involved in the formation of molybdenum carbide.…”

“…There are two main reasons for this decrease of specific surface area. On one hand, Mo species particles will block some of the pores; on the other hand, AC provides a carbon source for molybdenum carbide during carburization, and its microporous structure is damaged to a certain extent 21 . The decrease in the pore volume of the micropores may be due to the fact that Mo species are mainly distributed in the micropores 18,22 .…”

Post-combustion carbon capture

“…This principle was illustrated by Ma et al for a MCM41 sorbent with both micro-and mesopores. The mesopores were tailored using either hexadecyltrimethylammonium bromide (CTAB) as a soft template, or mesoporous carbon as a hard template [88]. These obtained materials showed a high CO2 adsorption capacity at CO2 pressures in excess of those applied in the VSA or TSA.…”