β-MCM41 composite molecular sieves were hydrothermally synthesized using NaOH treated β zeolite as precursors, and Pt/β-MCM41
bifunctional catalysts were prepared by impregnation. Hβ, desilicated Hβ by NaOH treatment (Dβ), and the physical mixture
of Hβ and MCM41 (β+MCM41) were also used as control supports for bifunctional catalysts. All the catalysts were characterized
by ICP, XRD, BET, nitrogen adsorption–desorption isotherm and NH3-TPD, and evaluated in the hydroisomerization of n-heptane using an atmospheric fixed bed flow reactor. Dβ, β+MCM41, or β-MCM41 supported Pt catalysts showed higher selectivity
to isoheptanes than the counterpart Pt/Hβ did due to the presence of mesopores in addition to the zeolite micropores. Moreover,
Pt/β-MCM41 was demonstrated to be a much more selective catalyst among them because the connection between mesopores and micropores
accelerated the diffusion of larger molecules of isoheptanes. Under optimal conditions, Pt/β-MCM41 provided a very high selectivity
to isomerization of 96.5%, coupled with a considerable high conversion of n-heptane of 56.0%.
Authors:B. Hunger, S. Matysik, M. Heuchel, E. Geidel, and H. Toufar
We have investigated the interaction of water with Na+-ion exchanged zeolites of different structures (LTA, FAU, ERI, MOR and MFI) by means of temperature-programmed desorption
(TPD). The non-isothermal desorption of water shows, depending on the zeolite type, differently structured desorption profiles.
In every case the profiles have, however, two main ranges. Using a regularization method, desorption energy distribution functions
have been calculated. The desorption energy distributions between 42–60 kJ mol−1, which can be attributed to a non-specific interaction of water, show two clearly distinguished energy ranges. The water
desorption behaviour of this range correlates with the electronegativity of the zeolites and the average charge of the lattice
oxygen atoms calculated by means of the electronegativity equalization method (EEM). The part of the desorption energy distributions
in the range of 60–90 kJ mol−1, reflecting interactions of water with Na+ cations, shows two more or less pronounced maxima. In agreement with vibrational spectroscopic studies in the far infrared
region, it may be concluded that all samples under study possess at least two different cation sites.
Authors:Bing Xue, Kai Jia, Jie Xu, Na Liu, Ping Liu, Chongfu Xu, and Yongxin Li
according to the BET equation.
The basicity of the samples was measured by CO 2 temperature-programmed desorption (CO 2 -TPD) on Quantachrome CHEMBET-3000. 0.200 g sample was pre-treated at 550 °C for 1 h in dry He flow (50 ml/min), and cooled
Authors:Jacek Przepiórski, Justyna Karolczyk, Tomoki Tsumura, Masahiro Toyoda, Michio Inagaki, and Antoni W. Morawski
) applying the same temperature program. Thus, carbon yield could be calculated as a balance between residual masses determined after TG analyses in argon and in air. The temperature programmed desorption (TPD) measurements were carried out with use of
Authors:Alexandre Carlos Camacho Rodrigues and José Luiz Fontes Monteiro
aromatization of the intermediates [ 2 ]. A lot of work on NH 3 -TPD, XPS, FTIR, ESR, NMR and EXAFS [ 15 – 19 ] done by several groups showed that impregnated Mo species are mainly located on the external zeolite surface. After calcination, part of Mo species
Authors:P. V. Surse, S. Wagholikar, S. Mayadevi, and S. Sivasanker
The surface area and acidity characteristics of H-beta were obtained, respectively, by N 2 adsorption and temperature programmed desorption (TPD) of NH 3 . The catalyst
Authors:Jianfei Ding, Rong Shao, Jun Wu, Zhangfeng Qin, and Jianguo Wang
-programmed desorption of ammonia (NH 3 –TPD) experiments. About 100 mg of sample was used in each measurement. The samples were pretreated at 500 °C for 1 h under argon stream (20 mL min −1 ). After that, the sample was cooled down to 100 °C, and pulse NH 3 (99
Authors:Jianfei Ding, Ligen Chen, Rong Shao, Jun Wu, and Wantian Dong
The catalyst alkalinity was measured on a quartz microreactor (TP-5080, Tianjin-Xianquan, China) through a temperature-programmed desorption of carbon dioxide (CO 2 -TPD) experiment. About 50 mg of sample was used in each measurement. The samples were
Authors:Jong Wook Bae, A Rong Kim, Seung-Chan Baek, and Ki-Won Jun
CO 2 conversion with time on stream. The promotional effect of CeO 2 –ZrO 2 was verified by measuring the changes of nickel crystallite size, reducibility and the extent of CO 2 activation with the help of TPR, H 2 -chemisorption, CO 2 -TPD and XRD