Hydrocarbon sorption

A. Morisato, B.D. Freeman, I. Pinnau and C.G. Casillas, Pure Hydrocarbon Sorption Properties of Poly(l-trimethylsilyl-l-propyne) [PTMSP] and Poly(l-phenyl-l-propyne) [PPP] and PTMSP/PPP Blends, J. Polym. Sci., Polym. Phys. Ed. 34, 1925 (1996). 

All of these mesoporous materials are characterized by having narrow pore size distributions comparable to microporous materials, and extraordinary hydrocarbon sorption capacities. These materials are important mostly because of their exceptional ordered mesopore structure, which is not common for other adsorbent materials. As a result, mesoporous-ordered silica has been proposed as a reference material for the study of adsorption processes in mesopores [16]. 

Zeolites show strong hydrocarbon sorption, which increases reactant concentration in the zeolite. This effect is more pronounced at low temperature. 

A key factor for the practical usefulness of aerogel-based hydrocarbon sorption systems is the reusability. Because aerogels are extremely expensive to produce (Chap. 26), some of the added cost must be compensated by exactly those types of practical aspects. As part of our preliminary studies on the reversibility of the sorption and desorption of superhydrophobic aerogels with various organics, the following trends were observed ... 

From the zeolite mordenite, Chen and Smith (82) obtained silica having the same zeolitic skeleton by repeatedly heating the hydrogen form in steam at 538 C and extracting the liberated aluminum with acid. The pores are apparently lined with siloxane oxygen bonds and are hydrophobic, retaining high hydrocarbon sorption capacity. 

The texture of dealuminated mazzites, prepared by combined steam and acid treatments, has been investigated by N2 and hydrocarbon sorption as well as Xe NMR spectroscopy [96D1]. The composition of the parent zeolite determines the volume and the size of the mesopores, both decreasing with aluminum content. 

Pan L, Liu H, Lei X, Huang X, Olson DH, Turro NJ, et al. RPM-1 a recyclable nanoporous material suitable for ship-in-bottle synthesis and large hydrocarbon sorption. Angew Chem Int Ed 2003 42 542-6. 

SOL Solovev, S.A., Yampolskii, Yu.P., Economou, I.G., Ushakov, N.V., and Finkelshtein, E.Sh., Thermodynamic parameters of hydrocarbon sorption by poly(silmethylenes) (Russ.),... 

Conformational Equilibria of the Guest Molecules FTIR studies relative to chlorinated hydrocarbons sorption into SPS films have shown that the trans conformation of DCE and i,2-dichloropropane (DCP) is largely prevailing in the clathrate phase, while the trans and gauche conformations are nearly equally populated when both chlorinated compounds are sorbed in the amorphous phase [88,137-139]. Because essentially only their trans conform-ers are included into the clathrate phases (both 8- and e clathrates), while both trans and gauche conformers are included in the amorphous phase, quantitative evaluations of vibrational peaks associated with these conformers allow the evaluation of the amounts of DCE and DCP confined as guest in the clathrate phase or simply absorbed in the amorphous phase [88,111,137-139]. 

Figure 10 Representative examples of literature-reported perfluorinated MOFs used for hydrocarbon sorption or separation, (a) Partially fluorinated [Cu(hfipbb)(H2hfipbb)o 5] synthesized from 4,4 -(hexafluoroisopropylidene)-bis(benzoic add). (b) Partially flu-orinated alkaline-earth polymer framework (AEPF)-l synthesized from 4,4 -(hexafluoroisopropylidene)-bis(benzoic add). (c) Fully fluorinated FMOF-2 synthesized from perfluorinated ligand 3,5-bis(trifluoromethyl)-l,2,4-triazolate (Flydrogen atoms and solvent molecules are omitted for clarity.)...

While addressing hydrocarbon sorption properties of MOFs, there has been intense debate on the commensurate adsorption of hydrocarbons using MOFs the mean munber of adsorbed hydrocarbon molecules relates to the symmetry of the framework topology, which is nearly impossible in routinely studied/used zeolites [109]. Jing Li et al. reported that adsorption capacity and location of molecules are specifically controlled by cavity size, shape, symmetry, and channel features such as chaimel segment [109]. Three different adsorption mechanisms have been offered for the sorption and separation of hydrocarbons (1) equilibrium (2) steric, and (3) kinetic. In some complex materials, it is possible that one or more mechanisms m operate at the same time. The equilibrium sorption and separation mechanism relies on... 

FIGURE 3.16 (Left) Building blocks of FMOF-1 (middle) water sorption studies in FMOF-1, BPC-Carbon and Zeolite-5A (right) water and hydrocarbon sorption studies in FMOF-1 [111]. (Reproduced Irom Yang, C. et al., ChemSoc 133,18094 (2011), with permission). 

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