An IR spectroscopy has been used to study the desorption of various bases on HF and LF OH groups in HY zeolite. It has been shown that the desorption temperature of adsorbates directly related to their geometric configurations and basicities. The adsorbates with different geometric configurations and similar basicities are adsorbed on LF OH-group, and their desorption temperatures at the same coverage are compared. The order of desorption temperature is NH3>(C2H5)3N>(n-C4H9)3N, and corresponds with the order of extent of molecular geometric configuration. For the adsorbates with similar geometric configurations and different basicities, performing above adsorption to obtain the same coverage, the order of desorption temperature is 2, 6-lutidine>piperidine for HF OH-groups, the order is just opposite to their basicities, it may be explained as follows: the 2, 6-lutidine with conjugate orbit via nitrogen atom bonding to HF OH-group to form greater bond energy than that of piperidine bonding to HF OH-group, the information explained that the formation of adsorption bond related to bonding type. In the same conditions, these adsorbates are adsorbed on LF OH-groups, the order of desorption temperature still corresponds to their basicities: piperidine>2, 6-lutidine>pyridine. The heats of desorption for NH3 adsorbed on HF or LF OH-groups in HY zeolite have also been measured by IR spectra, their values are 22.2kcal/mol on the HF OH-groups and 18.9kcal/mol on the LF OH-groups at the range of 218-341`C.

Key words: DETERMINATION, INFRARED SPECTROPHOTOMETRY, ZEOLITE, THERMAL DESORPTION