10.1039/c4cy00360h
Catalytic consequences of micropore topology, mesoporosity, and acidity on the hydrolysis of sucrose over zeolite catalysts
The conventional microporous FER, MFI, MOR, BEA, and FAU with different acidity (Si/Al ratio) were purchased from Zeolyst. MWW and PMWW were derived from the same precursor, MWW (P). The hydrothermal synthesis of MWW (P) was carried out by using the method described by Corma et al.39,40 One portion of the crystalline product MWW (P) was dried and calcined to produce MWW. The other portion of MWW (P) was swollen according to the method developed by Maheshwari et al.,41 followed by pillaring of the swollen materials using the procedure reported by Barth et al.38 The resulting solid was treated using the same conditions as those for MWW to produce PMWW. A multilamellar MFI was synthesized using the method reported by Ryoo and co-workers,43 through a coherent assembly of the zeolite layer and the structure directing agent, a diquaternary ammonium surfactant with a relatively long hydrocarbon chain. Pillaring of multilamellar MFI was done as reported by Na et al.42 to produce PMFI, using a similar pillaring procedure to that of swollen MWW (P). The as-synthesized MWW and MFI zeolites were ion-exchanged four times using 1 mol L-1 aqueous NH4NO3 (weight ratio of zeolite to NH4NO3 solution = 1:10) at 353 K for 12 h and subsequently collected by vacuum filtration, washed with deionized (DI) water three times, and dried at 343 K overnight. No ion-exchange process was applied to the commercial zeolites since they were purchased in the NH4+-form. All zeolite samples in their NH4+-form were treated in dry air (100 mL min-1, ultrapure, Airgas) by increasing the temperature from ambient temperature to 823 K at 1.45 K min-1 and holding for 4 h to thermally decompose NH4+ to NH3 and H+. To differentiate the same type of zeolite with different Si/Al ratios, each catalyst is named by its structure type and Si/Al ratio in the remainder of this paper.
aqueous NH4NO3
1 mol L-1
mol L-1
zeolite to NH4NO3 solution
weight ratio
1:10
as-synthesized MWW and MFI zeolites
ion-exchanged
353 K
K
as-synthesized MWW and MFI zeolites
ion-exchanged
12 h
h
as-synthesized MWW and MFI zeolites
dried
343 K
K
as-synthesized MWW and MFI zeolites
ion-exchanged
four times
times
deionized (DI) water
three times
times
zeolite samples in their NH4+-form
treated
100 mL min-1
mL min-1
zeolite samples in their NH4+-form
temperature
823 K
K
zeolite samples in their NH4+-form
increasing the temperature
1.45 K min-1
K min-1
zeolite samples in their NH4+-form
holding
4 h
h