|Budget Amount *help
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1997 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1996 : ¥1,500,000 (Direct Cost : ¥1,500,000)
Several inorganic phosphorus compounds were synthesized and their changes in structure, catalytic activity, and humidity-sensitivity by grinding were investigated.
1. Synthesis of several inorganic phosphorus compounds and their changes in catalytic activity and physicochemical property
When crystalline AIPO_4 which were synthesized in a mixture of organic solvent and water was ground, its catalytic activity for cis-2-butene isomerization was decreased, and its specific surface area, pore volume, and mean pore radius were decreased too. In the case of crystalline YPO_4 also, its catalytic activity for 1-butene isomerization was decreased, and its specific surface area and pore volume were decreased, although mean pore radius was increased. When crystalline Ti (HPO_4) _2・nH_2O and TiP_2O_7 were ground, their surface acidity was changed, and the activity for 1-butene isomerization as well as the specific surface area were increased. The increase in activity of those phosphates by grinding
was considered to be due to the exposure of an amorphous material involved in the bulk of them, and the transformation of the amorphous material to active species after calcination. The activity of BPO_4 for the oligomerization of cis-2-butene or propene was increased by grinding. The specific surface area was also increased, while the pore volume and mean pore radius were decreased. The activity was mainly ascribed to the presence of Bronsted acid sites, although the other factors such as pore volume and mean pore radius should be considered.
2. Effect of grinding of Ti (HPO_4)_2・nH_2O and Cu-P-Y composite oxides on their humidity-sensing characteristics The solid acidity of Ti (HPO_4) _2・nH_2O is closely related to its electric conductivity when it is placed in a wet atmosphere. The dependence of its electric resistance on humidity allows it to be utilized as a humidity sensor. In the manufacturing process. Ti (HPO_4) _2・nH_2O is subjected to grinding and heating. By such treatments, its acidic property will be changed and as a result the humidity-sensing characteristic will also be changed. Therefore, the humidity sensor prepared from Ti (HPO_4) _2・nH_2O which was ground before being pressed and heated was compared with that prepared from non-ground Ti (HPO_4) _2・nH_2O.However, contrary to expectation, there is no significant difference between them. Similar result was obtained for Cu-P-Y composite oxide sensor.