Halocarbon adsorption in nanoporous materials: A combined calorimetric and Monte Carlo study of trichloroethylene (TCE) in faujasite-type zeolites

Journal Article · Tue Nov 10 04:00:00 EST 1998 · Langmuir

DOI:https://doi.org/10.1021/la980318t· OSTI ID:316329

Mellot, C F; Cheetham, A K ^[1]; Harms, S ^[1]; Savitz, S; Gorte, R J; Myers, A L ^[2]

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1. Univ. of California, Santa Barbara, CA (United States). Materials Research Lab.
2. Univ. of Pennsylvania, Philadelphia, PA (United States). Dept. of Chemical Engineering

Isosteric heats of adsorption of trichloroethylene (TCE) in a series of faujasite-type zeolites, siliceous faujasite, NaY (Si:Al = 2.6), and NaX (Si:Al = 1.2), have been studied by the combination of calorimetry and (N,V,T) Monte Carlo simulations, varying the sorbate loading up to {approximately}35 molecules per unit-cell. Excellent agreement is obtained between observed and calculated heats, confirming the applicability of the force field to the realm of unsaturated halocarbons for a large range of Si:Al ratio, cation content, and sorbate loading. The relative contributions of short-range and long-range interactions to the heat of adsorption are discussed, and the host/guest pair distribution functions (PDFs) from the MC simulations are analyzed in detail. At fixed loading, TCE heats of adsorption increase in the sequence of host basicity and cation content: siliceous faujasite: {approximately}40 kJ/mol < NaY: {approximately}55 kJ/mol < NaX: {approximately}80 kJ/mol (extrapolated to zero loading). Such a correlation is further elucidated from the host/guest PDFs by the enhancement of H{sub TCE}{hor_ellipsis}O{sub ZEO} hydrogen bonding and Cl{sub TCE}{hor_ellipsis}Na{sub ZEO} electrostatic interactions from the siliceous faujasite to NaY and NaX. An increase in TCE loading gives rise to a systematic increase in adsorption heats (>10 kJ/mol); this is identified as of a predominantly dispersive nature arising from Cl{sub TCE}{hor_ellipsis} and H{sub TCE}{hor_ellipsis}Cl{sub TCE} intermolecular interactions.

• Sponsoring Organization: USDOE, Washington, DC (United States); National Science Foundation, Washington, DC (United States)
• DOE Contract Number: FG03-96ER14672
• OSTI ID: 316329
• Journal Information: Langmuir, Journal Name: Langmuir Journal Issue: 23 Vol. 14; ISSN LANGD5; ISSN 0743-7463
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
ADSORPTION
ADSORPTION HEAT
CALORIMETRY
CHLORINATED ALIPHATIC HYDROCARBONS
FAUJASITE
MONTE CARLO METHOD
SORPTIVE PROPERTIES