3788
J. Phys. Chem. 1996, 100, 3788-3798
Zeolite MCM-49: A Three-Dimensional MCM-22 Analogue Synthesized by in Situ Crystallization Stephen L. Lawton,† Anthony S. Fung,† Gordon J. Kennedy,*,† Lawrence B. Alemany,‡ Clarence D. Chang,§ George H. Hatzikos,† Daria N. Lissy,† Mae K. Rubin,† Hye-Kyung C. Timken,† Stefan Steuernagel,⊥ and Donald E. Woessner| Mobil Research and DeVelopment Corporation, P. O. Box 480, Paulsboro, New Jersey 08066, Department of Chemistry, Weiss School of Natural Sciences, Rice UniVersity, P. O. Box 1892, Houston, Texas 77251, Central Research Laboratory, Mobil Research and DeVelopment Corporation, P. O. Box 1025, Princeton, New Jersey 08540, Bruker Analytische Messtechnik GMBH, Silberstreifen, D-76287 Rheinstetten, Germany, and Department of Radiology, Southwestern Medical Center at Dallas, UniVersity of Texas, 5801 Forest Park Road, Dallas, Texas 75235 ReceiVed: September 25, 1995X
As-synthesized MCM-49 is a three-dimensional (3D) microporous aluminosilicate zeolite with the MCM-22 framework topology. It is formed hydrothermally in a reaction gel and is the first example of a zeolite with this topology to be produced by direct synthesis, in contrast with the conventional procedure in which a precursor is formed first and is then calcined. When hexamethyleneimine (HMI) is used as the directing agent, a SiO2/Al2O3 ratio of the framework as low as 17/1 can be achieved. X-ray powder diffraction (XRD), temperature programmed base desorption (TPBD) experiments, and multinuclear NMR analyses of this zeolite and others in this series (Viz., calcined MCM-22 and its precursor) provide new insights into the novelty of this class of materials. TPBD and 13C NMR experiments, for example, provide experimental evidence that support the coexistence of different dual pore systems within both the MCM-22 precursor and MCM-49. The 27Al MAS NMR spectra of MCM-22 and calcined MCM-49 exhibit three distinct Td resonances, a feature not previously observed for any other zeolite. And finally, aluminum enrichment of the T1-O1-T1 bridge in MCM-49 is postulated on the basis of the length of its unit cell c-parameter.
Introduction MCM-22 is synthesized hydrothermally in a reaction mixture with a variety of cyclic and heterocyclic amines as a directing agent.1,2 The product, of unknown structure and hereafter referred to as MCM-22 precursor or, simply, MCM-22(P), is characterized by an X-ray diffraction (XRD) powder pattern with sharp and broad peaks. Upon calcination at 538 °C the precursor undergoes a change in structure to produce a material (MCM-22) whose proposed three-dimensional framework topology contains unique and unusual structural features.3,4 The structure of hexagonal MCM-22 has been shown to consist of layers of atoms linked together along the unit cell c-axis by oxygen bridges. Within the layer is a two-dimensional sinusoidal channel system, accessible through 10-ring apertures. Void space between these layers is large, consisting of supercages whose inner free diameter, 7.1 Å, is defined by 12-rings and whose inner height is 18.2 Å. These large cages are also accessible through 10-ring apertures. There is no communication between the intralayer sinusoidal channels and the interlayer supercages. MCM-22(P) is synthesized when the mole ratio (Ro/Ri) of the organic template (Ro) to inorganic cations (Ri) in the reaction gel is typically greater than 2.0. When this ratio is decreased to a value less than 2.0, a material, MCM-49, is formed that exhibits an XRD pattern nearly identical with that for MCM22 but with distinct differences in peak positions and inten†
Mobil Research and Development Corp., Paulsboro, NJ. ‡ Rice University. § Mobil Research and Development Corp., Princeton, NJ. ⊥ Bruker Analytische Messtechnik GMBH. | University of Texas. X Abstract published in AdVance ACS Abstracts, January 15, 1996.
0022-3654/96/20100-3788$12.00/0
sities.5 (In this paper the name MCM-49 denotes just the “assynthesized” form.5b) Although the general similarities between their XRD patterns suggest that the framework topology of MCM-49 may be isostructural with that of MCM-22, the differences could be indicative of minor topological differences. Indeed, upon calcination at 538 °C, the differences in the XRD pattern disappear, indicating that in its calcined form the structure of MCM-49 is virtually identical with that of MCM22. We undertook an extensive investigation of MCM-49 using XRD, temperature programmed base desorption (TPBD), and multinuclear NMR to determine what differences, if any, exist between its structure and those of MCM-22(P) and MCM-22. Although we explored the use of different metals (Si, Al, B) and templates, we focused our attention primarily on the silicon/ aluminum (Si, Al) system with HMI as the directing agent. This new synthesis route made possible an opportunity to take a closer look at the MCM-22 family in ways not otherwise possible with the conventional synthesis. In this paper we report the results of our study. This study complements recent independent work conducted on MCM-22 and related materials6 and broadens our structural understanding of this new family of materials. Experimental Section Synthesis. Samples of MCM-22(P) and MCM-49 were produced in accordance with procedures outlined elsewhere.1,2,5 Samples synthesized with the directing agent HMI were the most extensively investigated, though in a few cases other organic amines (Viz., cyclopentylamine, cyclohexylamine, cycloheptylamine, and piperidine) were also studied. All reaction mixtures © 1996 American Chemical Society
MCM-22 Analogue Synthesized by Crystallization
Figure 1. Typical X-ray diffraction patterns of MCM-22(P), MCM49, and MCM-22.
were crystallized in a stainless steel reactor with agitation. The crystalline products were filtered, washed with water, and dried at 120 °C. Calcination. In most cases samples were calcined at 538 °C in ambient air for 16 h in a muffle furnace to remove the organic. Temperature ramping proceeded at a rate of 2.8 °C/ min. Under these conditions, mild steaming of the sample can occur. To minimize steaming effects, a few samples were heated with a flow of dry air at a rate of 5 (v/v)/min (volumes of gas per volume of catalyst per minute) during the temperature ramping stage and maintained at this rate while the temperature was held at 538 °C. X-ray Diffraction. X-ray powder diffraction data were obtained on a Scintag XDS2000 diffractometer equipped with a germanium solid state detector using copper KR radiation. The data were recorded by step-scanning at 0.02° 2θ per step, where θ is the Bragg angle, and a counting time of 10 s for each step. Typical diffraction patterns of MCM-22(P), MCM49, and MCM-22 are shown in Figure 1 and summarized in Tables 1 and 2. Peak positions and relative intensities were derived with the use of a profile fitting routine using the Pearson VII curve type. Assignment of Miller indices was based on the structure derived for calcined [B]MCM-22.3 In the absence of detailed
J. Phys. Chem., Vol. 100, No. 9, 1996 3789 precise knowledge of the structure of MCM-22(P), no attempt was made to index this material beyond that shown in Table 1. The hexagonal unit cell parameters, a and c, were determined by refinement of the indexed patterns.7 In the case of MCM22(P), the unit cell parameters were determined by refinement using unit weights of those reflections whose Miller indices were known with certainty assuming hexagonal symmetry. All other patterns (Viz., MCM-49, calcined MCM-49, and MCM-22) were refined using the σ of 2θ as weights (in the form 1/σ). The diffractometer zero point value was also refined and was typically (0.10°. The values of 2θobs and dobs (Å) summarized in Tables 1 and 2 have been corrected for this zero point error. The refined unit cell parameters for all samples examined by XRD are summarized in Table 3. A number in parentheses is two times the computed standard deviation in the least significant digit of the parameter for refinements with unit weights and is the actual computed standard deviation for weighted refinements. This number is a measure of the precision of the determination and not necessarily the accuracy. As a measure of accuracy in the alignment of the Scintag diffractometer, a crystalline quartz standard was scanned from 18 to 82° 2θ at 1 s/step and 0.02°/step. After correcting for background and stripping out the R2 peaks, the observed 2θ values of 16 peaks, derived by deconvolution, were subjected to a weighted, least-squares refinement; correction for the zero point error was included. The refined unit cell parameters for the hexagonal unit cell, based on Cu KR ) 1.5406 Å, were a ) 4.9199(3) and c ) 5.4117(3) Å. These are in good agreement with the theoretical values of a ) 4.9126(5) and c ) 5.4043(15) Å.8 The differences between the observed and the theoretical values of a and c are 0.15 and 0.14%, respectively. These small relative errors indicate that the unit cell parameters for MCM-22(P), MCM-22, and MCM-49 are reasonably accurate, even though an internal standard was not included in each sample. Determination of unit cell parameters for a given sample, using the Scintag X-ray diffractometer, was highly reproducible. To demonstrate this, MCM-49 sample B11 was ground, repacked, and rescanned on five separate occasions over a period of 7 months. Peak positions and corresponding σ values for each diffraction pattern were derived using the Scintag deconvolution software. Unit cell parameters were then refined by weighted least squares as described above. The average, weighted unit cell parameters and corresponding root-meansquare deviations9 were a ) 14.281(2) and c ) 25.37(2) Å. Experimental MAS NMR Procedures. 27Al MAS NMR spectra were obtained at four different field strengths (17.6, 11.7, 9.4, and 6.3 T). The 17.6 T spectra were recorded on a Bruker DMX 750 NMR spectrometer at 195.5 MHz, with 14 kHz spinning speeds, 2.0 µs excitation pulses, and 2.0 s recycle delays. The 11.7 T spectra were recorded on a Bruker AM500 NMR spectrometer at 130.31 MHz with 4-6 kHz spinning speeds, 1.0 µs excitation pulses (solution π/2 ) 6 µs), and 0.1 s recycle times. The 9.4 T spectra were obtained on a Bruker MSL-400 NMR spectrometer at 104.26 MHz with 5.00 kHz spinning speed, 1.0 µs excitation pulses (solution π/2 ) 6 µs), and 0.1 s recycle times. The low-field (6.3 T) spectra were obtained on Jeol FX-270 NMR spectrometer at 70.3 MHz with a Chemagnetics probe. The 27Al chemical shifts were referenced to 1 M aqueous solution of Al(NO3)3 at δ ) 0.0 ppm. The 27Al DOR NMR data were obtained at 4.7 T on a Chemagnetics CMX-200 NMR spectrometer at 52.13 MHz with 2.3 µs excitation pulses and 0.5 s pulse delays and at 9.4 T on a Bruker AMX-400 NMR spectrometer at 104.26 MHz with 2.5 µs excitation pulses and 1.0 s pulse delays. Inner rotor
3790 J. Phys. Chem., Vol. 100, No. 9, 1996
Lawton et al.
TABLE 1: X-ray Diffraction Data for MCM-22(P) and Its Calcined Product (Sample A5) as-synthesizeda hkl
2θobs
2θcalc
dobs (Å)
I/I0
001 002 100 101 102 111 004 200 201 202 210
3.1 6.53 7.14 7.94 9.67 12.85 13.26 14.36 14.70 15.85 19.00
3.3 6.60 7.15 7.88 9.74 12.84 13.22 14.34 14.72 15.80 19.00
28.5 13.53 12.38 11.13 9.14 6.89 6.68 6.17 6.02 5.59 4.67
14 36 100 34 20 6 4 2 5 4 2
4.47 4.12 4.05 3.95 3.77 3.57 3.43 3.36
22 10 19 21 13 20 55 23
3.06 2.833 2.768 2.677
4 3 2 5
2.573 2.472 2.418 2.379
1 2 1 5
300
220 310
320
500 330 a
calcinedb
19.85 21.56 21.94 22.53 23.59 24.98 25.98 26.56 29.15 31.58 32.34 33.48 34.87 36.34 37.18 37.82
21.58
24.96 26.00
31.56
36.35 37.83
hkl
2θobs
2θcalc
dobs (Å)
I/I0
002 100 101 102 111 004 200 201 202 203 105 211 212 300 301 302 214 220 310 312 117 216 314 320 404 323 218 413 500 502 330
6.94 7.17 8.03 9.94 12.89 14.06 14.36 14.77 15.98 18.01 19.02 19.37 20.28 21.61 21.92 22.71 23.76 25.01 26.03 26.98 27.82 28.65 29.75 31.65 32.29 33.41 34.45 34.92 36.40 37.10 37.88
7.02 7.16 7.98 10.04 12.91 14.06 14.35 14.78 15.99 17.84 19.03 19.35 20.30 21.60 21.89 22.74 23.74 24.99 26.03 26.99 27.77 28.60 29.70 31.60 32.31 33.40 34.36 34.99 36.40 37.11 37.88
12.74 12.34 11.02 8.90 6.87 6.30 6.17 6.00 5.55 4.92 4.67 4.58 4.38 4.11 4.06 3.92 3.75 3.56 3.42 3.30 3.21 3.12 3.00 2.827 2.772 2.682 2.603 2.569 2.468 2.423 2.375
41 100 51 46 11 8 35 10 13 2 3 3 10 10 20 29 15 14 61 13 9 6 1 3 3 6 2 2 1 1 4
a ) 14.27(3), c ) 26.8(2) Å. b a ) 14.251(9), c ) 25.19(5) Å.
spinning speeds of 3-4 kHz and outer rotor spinning speeds of 0.7-0.8 kHz were used in the DOR data collection. 13C CP/MAS NMR spectra were obtained on a Bruker MSL400 NMR spectrometer at 100.61 MHz using a contact time of 1 ms, a 5 s recycle delay, and a spinning rate of 3.1 kHz. The 13C chemical shifts were referenced to TMS using the methine resonance of adamantane (δ ) 38.3 ppm from TMS) as a secondary standard. 13C NMR solution spectra of HMI and HMI‚H+ were obtained on a Bruker AM-500 spectrometer at 125.76 MHz using a 9.1 µs pulse (π /2 pulse), composite pulse proton decoupling, and a 4 s recycle delay. Temperature Programmed Base Desorption Experiments. Samples A5 and B11 were chosen to represent MCM-22(P) and MCM-49, respectively, for the TPBD (TGA/titration) experiments because of their similar bulk Si/Al2 ratios (21 Vs 17). TPBD data of the samples were collected from 25 to 700 °C at a heating rate of 10 °C/min under flowing He using a DuPont 951 thermogravimetric analyzer. The effluent was bubbled continuously through a H3BO3/NH4Cl buffer solution. The pH of the buffer solution was kept constant by automatically titrating with a sulfamic acid solution. Results and Discussion Synthesis of MCM-22(P) and MCM-49. X-ray powder diffraction patterns (Figure 1) indicate that the as-synthesized materials MCM-22(P) and MCM-49 are distinct structural species. Both can be synthesized as pure materials and as mixtures and, in some cases, contaminated with other products such as ferrierite and/or mordenite. A factor that appears to influence formation of either MCM22(P) or MCM-49 is the mole ratio of the organic cation, Ro, to the inorganic cations, Ri, where Ri ) Na, K, or Rb. When
this ratio (Ro/Ri) is typically less than 2.0, formation of MCM49 is favored. When HMI is used, the silica/alumina ratios of the MCM-22(P) and MCM-49 products range from 21 to 31 and from 17 to 22, respectively. By increasing the relative proportion of alkali in the reaction gel, with formation of MCM49, more aluminum is incorporated into its framework than into the MCM-22(P) framework. Since both materials can also be synthesized as physical mixtures, an overlap in the silica/alumina ratio was found to occur in the range 19-25. MCM-22(P) can be synthesized with boron in the framework by using HMI as the directing agent. Synthesis of [B]MCM49 with HMI was unsuccessful. Marginal success, however, was achieved with piperidine, the product (sample C7) being a 50:50 mixture of [B]MCM-22(P) and [B]MCM-49. X-ray Diffraction. This series consists of three members: MCM-22(P), MCM-49, and MCM-22. A typical XRD powder pattern of each member is shown in Figure 1. The pattern of MCM-22(P), characterized by both sharp and broad peaks, is distinctly different from those of MCM-49 and MCM-22, which generally have just sharp peaks. The patterns of MCM-49 and MCM-22 are similar. However, to one skilled in the art, they exhibit distinct differences. Figures 2-4 depict key features that distinguish the various members. For a given framework composition the unit cell a-parameter is constant, whereas the c-parameter generally is not. Average values are summarized in Table 4. For samples with aluminum (Table 4) the average c-parameter for MCM22(P) is larger than that for MCM-49, which is larger than that for MCM-22. Because of this, the 002 and 004 peaks serve as visible, distinguishing markers in the XRD patterns in the regions 6-7.5° and 12-15° 2θ. Figure 2 shows the positions of the 002 peak (influenced only by the unit cell c-parameter)
MCM-22 Analogue Synthesized by Crystallization
J. Phys. Chem., Vol. 100, No. 9, 1996 3791
TABLE 2: X-ray Diffraction Data for MCM-49 and Its Calcined Product (Sample B7) as-synthesizeda
a
calcinedb
hkl
2θobs
2θcalc
dobs (Å)
I/I0
001 002 100 101 102 111 004 200 201 202 203 105 211 204 212 006 300 301 106 302 214 007 220 221 310 312 117 216 401 314 320 404 323 218 413 500 502 330
3.3 6.84 7.14 7.94 9.93 12.86 13.89 14.32 14.72 15.91 17.76 18.95 19.32 20.01 20.21 20.92 21.55 21.83 22.21 22.65 23.61 24.49 24.93 25.17 25.95 26.88 27.58 28.44 29.08 29.56 31.55 32.18 33.30 34.09 34.86 36.26 37.00 37.77
3.5 6.96 7.14 7.94 9.98 12.87 13.94 14.31 14.73 15.93 17.75 18.87 19.29 20.03 20.23 20.97 21.54 21.82 22.18 22.66 23.62 24.51 24.92 25.17 25.95 26.90 27.55 28.42 29.07 29.58 31.50 32.17 33.28 34.11 34.86 36.29 36.99 37.76
26.8 12.92 12.37 11.14 8.91 6.88 6.37 6.19 6.02 5.57 4.99 4.68 4.59 4.44 4.39 4.25 4.12 4.07 4.00 3.93 3.77 3.63 3.57 3.54 3.43 3.32 3.23 3.14 3.07 3.02 2.835 2.782 2.691 2.630 2.574 2.477 2.429 2.382
16 51 100 55 35 14 11 7 3 11 3 5 5 19 16 10 17 32 13 50 28 7 20 8 98 24 17 12 3 3 3 6 8 4 3 2 3 7
hkl
2θobs
2θcalc
dobs (Å)
I/I0
002 100 101 102 111 004 200 201 202 203 105 211
6.95 7.14 7.97 10.02 12.86 14.16 14.32 14.75 15.93 17.81 19.02 19.32
7.03 7.14 7.96 10.03 12.88 14.09 14.31 14.74 15.96 17.82 19.04 19.30
12.72 12.38 11.10 8.83 6.88 6.25 6.18 6.01 5.56 4.98 4.67 4.59
61 100 69 60 13 29 31 11 20 2 5 4
212 006 300 301 106 302 214 007 220 221 310 312 117 216 401 314 320 404 323 218 413 500 502 330
20.24 21.15 21.56 21.84 22.42 22.68 23.71 24.72 24.93 25.19 25.96 26.93 27.79 28.61 29.08 29.65 31.56 32.24 33.32 34.41 34.85 36.28 37.03 37.78
20.25 21.20 21.54 21.83 22.39 22.68 23.71 24.78 24.92 25.18 25.96 26.92 27.79 28.59 29.08 29.65 31.51 32.24 33.32 34.37 34.90 36.29 37.01 37.77
4.39 4.20 4.12 4.07 3.97 3.92 3.75 3.60 3.57 3.54 3.43 3.31 3.21 3.12 3.07 3.01 2.835 2.776 2.689 2.606 2.575 2.476 2.428 2.381
17 7 14 27 13 41 27 7 16 8 92 19 20 12 3 3 5 5 10 4 2 2 3 6
a ) 14.292(3), c ) 25.42(1) Å. b a ) 14.291(5), c ) 25.15(2) Å.
Figure 2. Deconvoluted XRD peaks with Miller indices 002 and 100 in typical patterns of the aluminum analogues of MCM-22(P), MCM49, and MCM-22. Note the movement of the 002 peak to higher 2θ as the unit cell c-parameter decreases.
relative to the permanently fixed 100 peak. Figure 3 shows the positions of the 004 peak relative to the moderately fixed 111 and permanently fixed 200 peaks. A continuum in c between each member is not observed. Another region that distinguishes MCM-22(P) from MCM49 and MCM-22 occurs between 26 and 29° 2θ, illustrated in Figure 4. In MCM-22(P) only one peak occurs in this region and is centered at ∼26.2° 2θ. It is broad and has a smooth, sloping tail that is visible on the high-2θ side. In MCM-49
and MCM-22 this feature is replaced by three sharp peaks, occurring in the approximate region 26.5-29.0° 2θ. Depending upon the synthesis conditions, MCM-22(P) and MCM-49 can cocrystallize as physical mixtures. Nonoverlapping XRD peaks originating from both components are clearly visible. A physical mixture can be detected by the three distinct regions in the XRD pattern discussed above. Figure 5 illustrates these distinguishing features. Location of HMI in the Structures. Although the structure of MCM-22(P) is not known, high-resolution electron micrographs have revealed that the basic layer of atoms that forms the sinusoidal channels in MCM-22 is also present in MCM22(P). Since MCM-22 contains, in addition to the intralayer sinusoidal channels, void spaces between the layers (the interlayer supercages), it is reasonable to expect that MCM22(P) will, likewise, contain some form of void space between its layers. We further anticipate that both regions of void space in MCM-22(P) will contain HMI. By extension, since MCM49 is synthesized directly in the reaction gel, it is logical to expect this material to contain HMI in the same regions as well. Depending upon its location and association with framework aluminum, it should be possible to detect the presence of HMI in these void spaces through the use of TPBD and 13C NMR experiments. TPBD (TGA/Titration) Data. The TGA curves of MCM22(P) (A5) and MCM-49 (B11) are shown in Figures 6 and 7, respectively. Their corresponding TPBD profiles are illustrated
3792 J. Phys. Chem., Vol. 100, No. 9, 1996
Lawton et al.
TABLE 3: Unit Cell Parameters (Å) for MCM-22(P), MCM-22, and MCM-49 as-synthesized product compn sample ID
X
Si/X2
MCM-22(P) a
organic, Ro
a
calcined 538 °C
MCM-49 c
a
c
MCM-22 System 14.27(2) 27.1(2) 14.26(4) 26.9(3) 14.26(3) 26.9(2) 14.26(3) 26.9(2) 14.27(3) 26.8(2) 14.26(4) 26.7(3) 14.26(4) 26.7(2) 14.26(3) 26.6(2) 14.25(7) 26.5(3) 14.09(3) 27.1(2) 14.07(3) 26.8(2)
A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11
Al Al Al Al Al Al Al Al Al Al, B Al, B
27 28 31 25 21 26 26 21 23 352, 26 177, 37
HMI HMI HMI HMI HMI HMI HMI HMI HMI HMI HMI
B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11 B12 B13 B14 B15
Al Al Al Al Al Al Al Al Al Al Al Al Al Al Al
21 19 31 18 17 18 19 18 22 17 17 17 17 27 26
HMI HMI CyHxA HMI HMI HMI HMI HMI HMI HMI HMI HMI HMI CyHpA CyPeA
C1 C2 C3 C4 C5 C6 C7
Al Al Al Al Al Al B
19 19 25 22 20 21 11
HMI HMI HMI HMI HMI HMI PIP
a
c
14.253(5)
25.11(2)
14.257(5)
25.12(2)
14.251(9) 14.267(7) 14.248(7) 14.257(6)
25.19(5) 25.16(5) 25.13(3) 25.16(4)
14.1145(8)b 14.124(10)
24.8822(18)b 24.88(3)
14.263(9) 14.284(6)
25.21(4) 25.26(2)
14.266(8)
25.19(6)
14.291(5)
25.15(2)
14.270(8)
25.23(5)
14.252(5) 14.276(8) 14.267(5)
25.13(2) 25.11(4) 25.22(3)
14.266(8) 14.275(5)
25.20(5) 25.14(2)
14.254(6)
25.16(3)
14.066(4)
24.78(1)
MCM-49 System 14.285(9) 14.297(8) 14.301(6) 14.275(9) 14.293(9) 14.298(6) 14.292(3) 14.292(8) 14.297(9) 14.289(15) 14.281(2)c 14.307(6) 14.289(5) 14.307(5) 14.295(7) Mixture of MCM-22(P) and MCM-49 14.269(9) 14.31(4) 26.9(3) 14.286(7) 14.29(2) 26.6(1) 14.27(3) 26.6(2) 14.27(3) 26.5(2) 14.27(4) 26.4(3) 14.00(3) 26.5(2) 13.988(5)
25.64(12) 25.54(4) 25.46(6) 25.45(7) 25.45(5) 25.42(3) 25.42(1) 25.41(5) 25.41(3) 25.39(5) 25.37(2)c 25.36(3) 25.35(2) 25.34(3) 25.28(2) 25.53(9) 25.42(2)
24.80(3)
Abbreviations are defined as follows: HMI ) hexamethyleneimine, CyHxA ) cyclohexylamine, CyHeA ) cycloheptylamine, CyPeA ) cyclopentylamine, and PIP ) piperidine. b Based on refined synchrotron data.3 c Unit cell parameters correspond to a weighted average of five repeat determinations. Numbers in parentheses correspond to the root-mean-square deviations; see text. a
TABLE 4: Average (Weighted) Unit Cell Parameters for MCM-22(P), MCM-49, and MCM-22a (Based on Table 3) sample type
tetrahedral framework atoms
a
c
no. of samples
MCM-22(P) MCM-49 MCM-22 MCM-22(P) MCM-49 MCM-22
Si, Al Si, Al Si, Al Si, B Si, B Si, B
14.26(1) 14.29(1) 14.27(1) 14.08(1) 13.99 14.11(3)
26.8(2) 25.39(9) 25.16(5) 27.0(2) 24.80 24.88(7)
9 15 17 2 1 3
a Numbers in parentheses correspond to the root-mean-square deviations.
TABLE 5: TGA/Titration Data for MCM-22(P) and MCM-49 sample
200-400 °C base (mequiv/g)
400-500 °C base (mequiv/g)
total base (mequiv/g)
MCM-22(P) MCM-49
0.84 0.46
1.16 1.11
2.00 1.57
in Figure 8. The weight loss profiles and basic gaseous species desorption curves of MCM-22(P) and MCM-49 are similar and can be classified into “low”- and “high”-temperature regimes: 200-400 °C and 400-500 °C, respectively. In the low-temperature regime, two well-defined base desorption peaks are observed in MCM-22(P) with maximum rates of desorption at 232 and 311 °C. These desorption peaks are
less resolved in MCM-49. Further, a larger amount of base is desorbed in the low-temperature regime with MCM-22(P) than with MCM-49 (cf. Table 5), consistent with a higher weight loss (37% Vs 30%) observed in the TPBD profile of MCM-22(P) than in that of MCM-49. In the high-temperature regime, the maximum rate of base desorption is observed at ∼467 °C. From 400-550 °C the amount of base desorbed from MCM22(P) is similar to that from MCM-49. These data for both materials are consistent with a dual pore system. 13C NMR Data. Shown in Figure 9 are the 13C CP/MAS NMR spectra of MCM-22(P) (A5) and MCM-49 (B11). The C1 carbon resonances of HMI occur at 49 and 57 ppm and the C2 and C3 resonances overlap at 27 ppm. The ratios of the peak areas at 27, 49, and 57 ppm are 4.0:1.1:0.7 and 4.0:1.5: 0.4 in the MCM-22(P) and MCM-49 spectra, respectively. Shown in Figure 10 for comparison are the 13C NMR solution spectra of HMI and HMI‚H+. Resonances corresponding to the three independent carbons are observed in each case and annotated directly on the figure. Interestingly, each signal is shifted to higher field upon protonation of the hexamethyleneimine. The observation of this protonation induced upfield shift is consistent with what has been previously reported for various aliphatic amines and N-heterocyclic six membered ring compounds.10,11 The 13C NMR chemical shift data are listed in Table 6.
MCM-22 Analogue Synthesized by Crystallization
J. Phys. Chem., Vol. 100, No. 9, 1996 3793
Figure 5. Example of an XRD pattern of cocrystallized mixtures of MCM-22(P) and MCM-49. Characteristic peaks with Miller indices [hkl] having l * 0 are visible for both components. Figure 3. Observed and deconvoluted XRD peaks in the region 1217° 2θ for typical patterns of the aluminum analogues of MCM-22(P), MCM-49, and MCM-22. Note the movement of the 004 peak to higher 2θ as the unit cell c-parameter decreases. (Dashed lines represent the observed peaks; solid lines, the deconvoluted peaks.)
Figure 6. TGA curve of as-synthesized MCM-22(P) (sample A5).
TABLE 6:
13C
sample Figure 4. Observed and deconvoluted XRD peaks in the region 2431° 2θ for typical patterns of the aluminum analogues of MCM-22(P), MCM-49, and MCM-22. A smooth, sloping tail on the high 2θ side of the 26.2° peak is a typical feature for MCM-22(P). After calcination, the 26.2° peak in MCM-22(P) disappears, and three new peaks emerge in the region 26.5-29.0° 2θ. These same three peaks are also present in the pattern of MCM-49. (Dashed lines represent the observed peaks; solid lines, the deconvoluted peaks.)
It has been shown that the 13C CP/MAS NMR spectra of occluded organic directing agents in synthetic zeolites are sensitive to the geometry of the intracrystalline void space in which they are located.12-16 For example, the 13C CP/MAS spectra of high silica zeolite A (ZK-4) contain two distinct resonances corresponding to TMA+ (tetramethylammonium) trapped in the R and β cages of the zeolite framework.12
MCM-22(P)a MCM-49a HMI HMI‚H+
NMR Chemical Shifts (ppm from TMS) C1 56.8, 48.5 56.8, 48.5 48.9 45.6
C2
C3
26.7 26.7 31.0 26.6
26.7 26.7 26.7 24.9
a C and C carbon resonances of HMI overlap in MCM-22(P) and 2 3 MCM-49.
Interestingly, two resonances are observed for the C1 of HMI in the 13C spectra of the MCM-22(P) and MCM-49 (Figure 9). These two C1 resonances could be due to (i) decomposition of the HMI, (ii) a mixture of protonated and nonprotonated HMI, and/or (iii) the presence of two distinct void spaces in which the HMI can reside. The ratio of the C2/C3 peak area to the C1 peak area in each sample is close to 2:1. Thus, it is unlikely that the second C1 resonance (57 ppm) is due to decomposed
3794 J. Phys. Chem., Vol. 100, No. 9, 1996
Lawton et al.
Figure 7. TGA curve of as-synthesized MCM-49 (sample B11).
Figure 9. 13C CP/MAS NMR spectra of as-synthesized MCM-22(P) (sample A5) and as-synthesized MCM-49 (sample B11). Figure 8. Comparison of the TPBD profiles of MCM-22(P) and MCM49.
HMI, suggesting that the HMI in both materials is intact. In addition, a comparison of the 13C spectra in Figure 9 with those of HMI and protonated HMI in Figure 10 confirms that the HMI is incorporated intact in the synthesis and that the second C1 resonance observed in the solids spectra is not due to protonated HMI. That is, these data indicate that the two C1 resonances are not simply due to the presence of a mixture of protonated and unprotonated HMI residing in the same environment. In fact, if both species were present, their C1 resonances should overlap in the 45-49 ppm region of the spectrum. Therefore, the observation of the two resonances for the C1 of HMI in MCM-22(P) and MCM-49 suggests that HMI may reside in two distinct environments within these two materials. Interpretation of TPBD and NMR Data. The intact incorporation of HMI during the synthesis of MCM-22(P) and MCM49 is further substantiated by TPBD experiments. On the basis of the weight loss and base desorption data in the low- and high-temperature regimes, the molecular weight of the decomposing species is estimated to be 112 and 96 g/mol in MCM22(P) and 95 and 89 g/mol in MCM-49. The similarity of the molecular weight of the decomposing species to that of HMI (molecular weight ) 99.2 g/mol) indicates that HMI survives the hydrothermal synthesis conditions and remains intact in the zeolites. The maximum rate of base desorption also coincides with the maximum rate of weight loss. Evidently, the HMI desorption is instantaneous without significant readsorption. However, the pathway by which HMI desorbs, either by diffusing out from the zeolite or by decomposition, cannot be determined in this work.
As the HMI desorption occurred at temperatures higher than the boiling point of HMI (138 °C), those desorbed in the lowtemperature regime were not physisorbed on the external surface of the zeolite crystal. The bimodal weight loss and base desorption profiles observed for as-synthesized MCM-22(P) and MCM-49 suggest that HMI probably resides in two distinct environments and leads to a difference in the pathway by which HMI is desorbed. This suggestion is consistent with the results of 13C NMR. In view of the evidence that HMI resides in two distinctly different environments both in MCM-22(P) and MCM-49, one should expect a difference in the desorption kinetics of HMI from these two locations. Investigations on the uptake of 2,2dimethylbutane on calcined MCM-22 indicate that there are three hydrocarbon uptake steps affected by the pore opening and channel structure of the zeolite. The slowest step is due to the hydrocarbon uptake into the confined intralayer channel. Similar qualitative arguments can be applied towards the desorption kinetics of HMI from MCM-22(P) and MCM-49. The high-temperature peak is assigned to the desorption of HMI from the intralayer channel. The appearance of this hightemperature peak at ∼467 °C may suggest that the template is “trapped” within this channel. This trapped HMI can only be removed by decomposition. This speculation is consistent with the temperature ranges at which the decomposition of adsorbed amines in ZSM-5 occurs.17 Those HMI species residing in the interlayer region, on the other hand, account for the desorption in the low-temperature regime. Distribution of HMI in these two void spaces appears to be related to the structural differences between MCM-22(P) and MCM-49. Assuming that the desorption temperature regimes can be correlated with the location of HMI in the structure, TPBD and 13C NMR data can provide a more quantitative
MCM-22 Analogue Synthesized by Crystallization
J. Phys. Chem., Vol. 100, No. 9, 1996 3795
Figure 11. View of the T1-O1-T1 bridge and “buried” T4 site in the structure of MCM-22. Except for O1, only T atoms are shown.
Figure 10. 13C NMR spectra of hexamethyleneimine (HMI) and protonated hexamethyleneimine (HMI‚H+).
estimate of the amount of HMI residing in each regime. For example, the TPBD data in the high-temperature regime indicate that the MCM-22(P) and MCM-49 investigated in this study have similar amounts of HMI located within the intralayer channel (1.16 Vs 1.11 mequiv/g, respectively). Using the expression X ) (1000N)/FW, where X is the amount of HMI in mequiv/g of zeolite, N is the number of HMI per unit cell in the intralayer channel, and FW is the formula weight of one unit cell, the observed average mequiv/g, 1.14, corresponds to ∼5.5 HMI per unit cell. This is equivalent to the empirical formula R0.077[Al0.077Si0.923O2], which is just that typically seen for MCM-22(P). Two sites exist within the sinusoidal channel that may ideally accommodate protonated HMIsthe midpoint of the 4258 cage (located on Wyckoff position 3g in space group P6/mmm at 1/2,0,1/2) and the 3-fold axis outside this cage (on Wyckoff position 2d at 1/3,2/3,1/2). Depending upon the orientations that HMI could adopt at each site relative to the unit cell c-axis, there appears to be sufficient room in the channel to have full occupancy in both sites. In so doing, a total of five HMI per unit cell is possible. The fact that slightly more than five is observed experimentally may indicate that additional “stuffing” of the channel can occur. When comparing the TPBD data of MCM-22(P) with MCM49 in the low-temperature regime (seen visually in Figure 8), we find that MCM-22(P) has approximately twice as much HMI incorporated in the interlayer region (0.84 Vs 0.46 mequiv/g). Intensities of the two C1 resonances in the NMR spectra reflect the HMI population in each of these two environments. The ratio of these two HMI species in the present samples are 0.62:1 [MCM-22(P)] and 0.26:1 (MCM-49). These results are in good agreement with the TPBD data. The NMR data support the hypothesis that the more intense peak (at 48 ppm) is associated
with HMI in the intralayer channel and corresponds to the hightemperature desorption peak in the TPBD profile. Similarly, the smaller peak (at 57 ppm) is associated with HMI in the interlayer region and corresponds to the low-temperature desorption peak. MCM-49: The c-Parameter Puzzle. Striking similarities in the XRD powder patterns of MCM-22 and MCM-49 indicate that the two framework topologies are probably identical. The fact that the average unit cell c-parameter (Table 4) is ∼0.2 Å longer in [Al]MCM-49 than in [Al]MCM-22 is therefore intriguing. We initially considered the possibility that the mere presence of HMI in the pores induced an expansion of the c-parameter. However, subsequent TPBD/XRD studies that tracked the change in c-parameter with desorption of HMI from MCM-22(P) and MCM-49 as a function of temperature ruled this out. These studies showed that the thickness of the layers in the MCM-22/49 framework is not influenced by the presence of HMI in the intralayer pores and that the unit cell c-parameter of MCM-49 is not significantly altered by removal of HMI from the interlayer region. The MCM-22/49 framework is therefore apparently quite rigid. Another possible explanation is preferential siting of aluminum in the framework position T1, a key site in the interlayer bridge. Location of this bridge in the framework structure is depicted in Figure 11. Evidence that aluminum siting at T1 may influence the value of c originates with the method of synthesis. Recall that MCM49 forms in situ in a reaction gel having a much higher alkali concentration than is used to synthesize MCM-22(P). The alkali ions, therefore, may serve to influence formation of this bridge, and if so, T1 may become a primary site for aluminum for charge balance. Since Al-O bonds (1.75 Å in length) are longer than Si-O bonds (1.61 Å in length), the difference, 0.14 Å, may account for some of the observed difference between the c-parameters of MCM-49 and MCM-22. Depending upon the mechanism of in situ bridge formation, it is even possible that some T1-O1-T1 bridges in MCM-49 might contain isolated Al-O-Al, which would then introduce a further increase of up to a maximum of 0.28 Å. If T1 is aluminum-rich, there would then have to be sufficient loss of Al from this site during calcination to account for the reduction in c to the value observed for MCM-22.
3796 J. Phys. Chem., Vol. 100, No. 9, 1996
Figure 12. 27Al MAS NMR spectra of MCM-22(P) (sample A5): (a) at 11.7 T (130.31 MHz); (b) at 6.3 T (70.37 MHz).
XRD data of MCM-49 crystals that contain tetrahedrally coordinated boron in the framework may present a different story. Although only one sample (C7) was available for study, curiously, the unit cell c-parameter of its as-synthesized form and its calcined form are identical (Viz., 24.80(3) Vs 24.78(1) Å, respectively) within 1σ. In view of the observed difference of ∼0.2 Å for the aluminum analogue, this was not expected. Boron has a smaller covalent radius than does silicon, resulting in a shorter T-O bond length; a difference in c would therefore have been expected. The fact that a difference was not observed may be an indication that boron sites in [B]MCM-49 differ from those in [Al]MCM-49. More specifically, perhaps the T1-O1T1 bridge in [B]MCM-49 does not contain boron, in contrast with the proposal for [Al]MCM-49. This could partially explain why [B]MCM-49 is so difficult to synthesize in pure form. Pure samples of the boron analogue will be required before a full evaluation can be made. 27Al MAS NMR Studies. The 27Al MAS NMR spectra of framework aluminosilicates usually consist of one tetrahedral (Td) Al resonance in the 54-68 ppm region of the spectrum that reflects the average environment of an Al atom in the tetrahedral framework.18 The 27Al MAS NMR spectra of MCM22(P) and the as-synthesized MCM-49 are both comprised of at least two Td resonances centered at ∼50 and ∼56 ppm. The calcined forms of both exhibit a third Td resonance at ∼61 ppm. This peak at 61 ppm is also observed in the very high field (17.6 T) spectrum of as-synthesized MCM-49 and as a shoulder in MCM-22(P) (Figures 14 and 15). Hunger et al.6f very recently also reported three Td signals in the Al spectra of samples of MCM-22. The observation of more than one Td resonance for a zeolite is rare. Prior to this work on MCM-22, zeolites Omega19 and ZSM-1820 were the only known cases of
Lawton et al.
Figure 13. 27Al MAS NMR (9.4 T) data of, from top to bottom, assynthesized MCM-22(P) (sample A1), after calcination at 311 °C/3 h, after calcination at 311 °C/6 h, and after calcination (MCM-22) at 538 °C/16 h.
zeolites that exhibit two Td Al resonances. In addition, the uniqueness of the MCM-22/49 framework is further illustrated by the observation that one of the three Td Al resonances (at δ ) 50 ppm) falls outside the spectral region that has been typically ascribed to zeolites. Similarly, previous work4 has shown that highly siliceous MCM-22 gives an unusually wide range of 29Si chemical shifts. The origin of the additional Td Al resonances in MCM-22 and MCM-49 could be due to either a second order quadrupolar interaction or additional Td Al species (as is the case in Omega and ZSM-18). These two possible explanations for the observed spectral features in MCM-22 and MCM-49 were investigated by multiple field and double rotation (DOR) NMR experiments. The low-field (6.3 T) and high-field (11.7 T) 27Al MAS NMR spectra of a MCM-22(P) (sample A5) are shown in Figure 12. The low-field spectrum shown in Figure 12b exhibits no significant line broadening and two distinct components with the same chemical shifts as those observed at higher field (Figure 12a). DOR NMR experiments, which are designed to remove anisotropic second order quadrupolar interactions, showed no improvement in resolution, thus confirming that the Al species have small quadrupolar coupling constants and are apparently in highly symmetric environments. These data indicate that no significant second order quadrupolar interactions are present and that the additional Td Al resonances in MCM-22(P), MCM-22, and MCM-49 are due to distinct Td Al species. Shown in Figure 13 from top to bottom are the 9.4 T 27Al MAS NMR spectra of as-synthesized MCM-22 (sample A1), after calcination at 311 °C/3 h, after calcination at 311 °C/6 h, and after calcination at 538 °C/16 h. The top three spectra are essentially identical and consist of two Td Al resonances in the
MCM-22 Analogue Synthesized by Crystallization
J. Phys. Chem., Vol. 100, No. 9, 1996 3797
Figure 14. Very high field (17.6 T) 27Al MAS NMR spectra of (a) MCM-22(P) and (b) MCM-22 (sample A1). An asterisk (*) denotes spinning side band from octahedral peak at 0.0 ppm.
Figure 15. Very high field (17.6 T) 27Al MAS NMR spectra of (a) MCM-49 and (b) calcined MCM-49 (sample B13). An asterisk (*) denotes spinning side band from octahedral peak at 0.0 ppm.
ratio of ∼60:40. Comparison of the spectra of the assynthesized and calcined (538 °C/16 h) forms of MCM-22 show that (i) ∼15% of the framework Al has come out during calcination to form Oh Al, resulting in an increase in the framework silica/alumina ratio to 45, and (ii) the appearance of a third Td Al resonance at 61 ppm after calcination indicates that structural changes may have occurred in the tetrahedral framework during calcination. The spectral data in Figures 12-15 are consistent with those previously published by Unverricht et al.,6a Hunger et al.,6f and Kolodziejski et al.6g However, these authors did not propose detailed structural interpretation of their spectral data. What follows is our interpretation of how these unique spectral features relate to the proposed structure. As discussed above, the multiple Al species observed in the NMR spectra are likely due to inherent structural components. In fact, experiments at the highest magnetic field currently available (17.6 T) unambiguously confirm the presence of a third Td peak in MCM-22 (Figure 14). The increased spectral dispersion and resolution at this field also make the determination of the relative peak areas straightforward. The spectrum of MCM-22 in Figure 14 can be simulated in terms of three overlapping Gaussian peaks at 61, 56, and 50 ppm in the ratio of 15:62:23. Lippmaa et al.21 showed that the isotropic chemical shifts of tetrahedral Al correlate well with average Al-O-Si angles in zeolite frameworks. Shown in Table 7 are the average T-O-T angles, the populations per unit cell for each of the crystallographically distinct sites that Al can occupy, and the 27Al chemical shifts predicted from that correlation for each of these T sites. Fitting the predicted chemical shift data to a three-line spectrum, arising from the overlap of the individual resonances from different T sites with random Al distribution, gives three peaks with relative areas of 17:50:33. Considering the empirical nature of the bond angle-chemical shift correlation, there is good agreement
TABLE 7: Crystallographic and 27Al MAS NMR Data for MCM-22 T site
population
av T-O-T angle
T6 T7 T8 T5 T4 T1 T3 T2
3 3 3 1 1 1 3 3
161.5 158.5 154.8 154.5 153.8 153.8 150.5 143.0
predctd shift
27Al
51 52 55 55 55 55 57 61
observed shift
27Al
50 50 56 56 56 56 56 60
between the predicted and experimental data. Thus, the experimental 27Al MAS NMR spectrum of calcined MCM-22 is consistent with its unique and unusual framework topology. This comparison of the predicted and experimental data suggests that the experimental spectrum can be tentatively assigned as in Table 7. Interestingly, the observed (T1, T3, T4, T5, T8): T2 ratio is 20% higher than would be expected for a totally random distribution of A1 throughout the framework (62:23 vs 50:33). This observation suggests that one or more of sites T1, T3, T4, T5, and/or T8 is aluminum-rich and that T2 is Al-deficient. Comparison of the 27Al MAS spectra of MCM-22 and MCM49 reveals some subtle yet interesting differences. Shown in Figure 15 are the 17.6 T 27Al MAS NMR spectra of a MCM49 (sample B13) before and after calcination at 538 °C/16 h. Comparison of the spectra of as-synthesized MCM-49 with MCM-22(P) shows that the 61 ppm resonance is clearly visible for as-synthesized MCM-49 but is only marginally visible as a shoulder for MCM-22(P). In the case of MCM-22(P) this peak becomes readily apparent upon calcination. The observation of the 61 ppm resonance in the as-synthesized MCM-49 is further evidence for the structural similarity of as-synthesized
3798 J. Phys. Chem., Vol. 100, No. 9, 1996 MCM-49 and MCM-22. Complete removal of the hexamethyleneimine by high-temperature calcination results in an 27Al MAS NMR spectrum that is similar to that of fully calcined MCM-22, with three peaks of relative area 13:64:23, again illustrating the similarity of MCM-22 and MCM-49. An interesting aspect of the 27Al MAS spectra in Figures 14 and 15 is that the observation of the resonance at 61 ppm indicates that calcination causes large enough changes in the the average T2-O-Tn angles (where n ) 1, 3, 3, and 4) to shift the T2 resonances. Although the exact nature of these calcination induced structural changes is unclear, the spectra of the calcined MCM-22 and MCM-49 reflect the similarity of these two materials. Summary and Conclusions We have shown that MCM-22(P) and MCM-49 can be synthesized in the Al and B systems with a variety of cyclic and heterocyclic amines. This new class of materials exhibits the following properties: (i) The framework topology of MCM49, prepared by direct synthesis, is considered to be similar to or identical with that of MCM-22. (ii) The unit cell c-parameter for [Al]MCM-49 is about 0.2 Å longer than that for [Al]MCM22. The exact cause of this increased length is not known, but may be associated with the unique distribution of aluminum in the framework. One possible consideration is the presence of aluminum in the T-O-T bridge linking the layers together. (iii) When using HMI as the directing agent during synthesis, the sinusoidal channels in [Al]MCM-22(P) and [Al]MCM-49 are fully saturated with equivalent amounts of HMI (∼5.5 per unit cell). The interlayer region of MCM-22(P), on the other hand, has about twice as much HMI than does MCM-49. (iv) [Al]MCM-49 made with HMI contains more framework aluminum than does MCM-22(P); when made with cyclic amines, the aluminum content tends to be the same as that in MCM22(P). (v) HMI in the aluminum analogues of MCM-22(P) and MCM-49 exhibit desorption rate maxima at three different temperatures. For [Al]MCM-22(P) and [Al]MCM-49, the temperatures are ∼232, ∼311, and ∼467 °C. The two lowtemperature TPBD profiles are considered to be associated with desorption of HMI from channels in the interlayer region of the framework structure, and the high-temperature profile is considered to be associated with the desorption of HMI from channels in the intralayer region of the framework structure. (vi) 27Al MAS NMR spectra of [Al]MCM-22(P) and MCM-49 display at least two Td resonances at ∼50 and ∼56 ppm. When these materials are calcined at 538 °C, their spectra clearly exhibit a third distinct Td resonance at ∼61 ppm. The observation of two Td Al resonances for a zeolite is rare; the presence of three is new and reflects the uniqueness of the threedimensional framework. Acknowledgment. The authors would like to thank Dr. Cynthia Ridenour of Otsuka Electronics and Dr. Martine Ziliox
Lawton et al. of Bruker Instruments for performing the 27Al DOR NMR experiments at 4.7 and 9.4 T, respectively. We are grateful to the management of Mobil Research and Development Corp. for permission to publish this work. References and Notes (1) Rubin, M. K.; Chu, P. U.S. Pat. 4,954,325, 1990. (2) Chang, C. D.; Mitko, D. M. U.S. Pat. 5,173,281, 1992. (3) Leonowicz, M. E.; Lawton, J. A.; Lawton, S. L; Rubin, M. K. Science 1994, 264, 1910. (4) Kennedy, G. J.; Lawton, S. L.; Rubin, M. K. J. Am. Chem. Soc. 1994, 116, 11000. (5) (a) Bennett, J. M.; Chang, C. D.; Lawton, S. L.; Leonowicz, M. E.; Lissy, D. N.; Rubin, M. K. U.S. Pat. 5,326,575, 1993. (b) The name MCM-49 was first introduced into the patent literature with this patent. It avoids confusion with the phrase “as-synthesized MCM-22” sometimes used for the MCM-22 precursor that is formed in the conventional synthesis. (6) (a) Unverricht, S.; Hunger, M.; Ernst, S.; Karge, H. G.; Weitkamp, J. Zeolites and Related Microporous Materials: State of the Art 1994, Part A; Studies in Surface Science and Catalysis 84; Elsevier: Amsterdam, 1994; p 37. (b) Ravishankar, R.; Sen, T.; Ramaswamy, V.; Soni, H. S.; Ganapathy, S.; Sivasanker, S. Zeolites and Related Microporous Materials: State of the Art 1994, Part A; Studies in Surface Science and Catalysis 84; Elsevier: Amsterdam, 1994; p 331. (c) Corma, A.; Corell, C.; Pe´rezPariente, J. Zeolites 1995, 15, 2. (d) Chan, I. Y.; Labun, P. A.; Pan, M.; Zones, S. I. Microporous Mater. 1995, 3, 409. (e) Millini, R.; Perego, G.; Parker, W. O., Jr.; Bellussi, G.; Carluccio, L. Microporous Mater. 1995, 4, 221. (f) Hunger, M.; Ernst, S.; Weitkamp, J. Zeolites 1995, 15, 188. (g) Kolodziejski, W.; Zicovich-Wilson, C.; Corell, C.; Pe´rez-Pariente, J.; Corma, A. J. Phys. Chem. 1995, 99, 7002. (h) Ravishankar, R.; Bhattacharya, D.; Jacob, N. E.; Sivasanker, S. Microporous Mater. 1995, 4, 83. (i) Corma, A.; Corell, C.; Forne´s, V.; Kolodziejski, W.; Pe´rez-Pariente, J. Zeolites 1995, 15, 576. (7) Williams, D. E. LCR-2, A Fortran Lattice Constant Refinement Program; Report IS-1052, Ames Laboratory, Iowa State University: Ames, IA, 1964. (8) International Tables for X-ray Crystallography; Vol. III; The Kynoch Press: Birmingham, England, 1962; p 122. (9) Lawton, S. L.; Kokotailo, G. T. Inorg. Chem. 1969, 8, 2410. (10) Stothers, J. B. Carbon-13 NMR Spectroscopy; Academic Press: New York, 1972; p 153. (11) Morishima, I.; Yoshikawa, K.; Okada, K.; Yonezawa, T.; Goto, K. J. Am. Chem. Soc. 1973, 95, 165. (12) Jarman, R. H.; Melchior, M. T. J. Chem. Soc., Chem. Commun. 1984, 414. (13) Hayashi, S.; Suzuki, K.; Shin, S.; Hayamizu, K.; Yamammoto, O. Chem. Phys. Lett. 1985, 113, 368. (14) Boxhoorn, G.; Van Santen, R. A.; van Erp, W. A.; Huis, G. R.; Clague, D. J. Chem. Soc., Chem. Commun. 1982, 264. (15) Nagy, J. B.; Gabelica, Z.; Derouane, E. G. Zeolites 1983, 3, 43. (16) Engelhardt, G.; Michel, D. High Resolution Solid State NMR of Silicates and Zeolites; Wiley: NewYork, 1987; p 348. (17) Parrillo, D. J.; Adamo, A. T.; Kokotailo, G. T.; Gorte, R. J. Appl. Catal. 1990, 67, 107. (18) Engelhardt, G.; Michel, D. High Resolution Solid State NMR of Silicates and Zeolites; Wiley: New York, 1987. (19) Fyfe, C. A.; Gobbi, G. C.; Kennedy, G. J.; Graham, J. D.; Ozubko, R. S.; Murphy, W. J.; Bothner-By, A.; Dadok, J.; Chesnick, A. S. Zeolites 1985, 5, 179. (20) Schmitt, K. D.; Kennedy, G. J. Zeolites 1994, 14, 635. (21) Lippmaa, E.; Samoson, A.; Magi, M. J. Am. Chem. Soc. 1986, 108, 1730.
JP952871E
