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A series of poly(mono n-alkyl itaconate)s, poly(methyl n-alkyl itaconate)s and poly(di n-alkyl itaconate)s with n=12, 14, 16, 18 and 22 have been prepared by radical polymerization. NMR studies point out that poly(methyl n-alkyl itaconate)s and poly(di n-alkyl itaconate)s are mainly syndiotactic polymers whereas poly(mono n-alkyl itaconate)s are obtained as almost atactic polymers. The characterization...
A series of highly crystalline silicoaluminophosphates having the AFI topology (SAPO-5) were synthesized with silicon content varying from 0 (AlPO 4 -5) to 0.11 molar fraction. As the silicon content increases, the total acidity per gram of solid, as determined by temperature programmed desorption of ammonia (NH 3 -TPD), also increases. However, the number of total acid sites per Si...
The transformation of α-pinene was studied in both gas and liquid phase over a series of faujasite‐like zeolites having different framework composition. A comparison with an amorphous silicoaluminate having 13 wt% of Al2O3 (SA) was made. Camphene + limonene were the major products observed in liquid phase at 393 K at conversion levels lower than 90%. At 473 K, where the reaction in gas phase took...
The interlayer complexes of several methyl methacrylate (MMA)/2-(N-methyl-N,N-diethylammonium iodide) ethyl acrylate (MDEA) copolymers with two smectite clays (bentonite and hectorite), synthesized in two different ways, were studied by means of solid state 13 C n.m.r. techniques. Given the relatively high content of paramagnetic centres in bentonite, which is approximately 50 times more paramagnetic...
7 1 Ga MAS n.m.r. analysis and the catalytic behavior during the transformation of 1-butene and n-butane strongly suggest the incorporation of Ga into the AlPO 4 -11 (AEL) framework during the synthesis of GaAPSO-11. A unique clear signal at around +120 ppm is proposed to be associated with the presence of tetrahedral Ga in the AEL framework of the unmodified GaAPSO-11. Migration...
XRD-pure SAPO-31 and SAPO-11 molecular sieves were obtained from the same synthesis gel, free of seeding, with a relatively low DPAP 2 O 5 ratio (0.3) after 40 and 120 h of crystallization, respectively, at 353 K. The phase transformation sequence was closely followed by XRD. The initial formation of the dense phases berlinite (B) and cristobalite (C) in the starting gel at a defined...
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