EFFECT OF PHOSPHORUS ON THE HYDROCRACKING CATALYSTS.

The effect of the added phosphorus on the hydrocracking catalysts containing Ni and Mo supported on alumina-zeolite was studied, using UV-Visible Diffuse Reflectance Spectra to determine the spinel NiAl//2O//4, and chromatographic technique to measure the surface acidity. The results show that the added phoshorus inhibits the formation of the spinel NiAl//2O//4 and reduces the acidity of the catalysts. It would be best to add phosphorus in the form of (NH//4)//2HPO//4, NH//4H//2PO//4, and (NH//4)//3PO//4, which can effectively inhibit the formation of spinel and affect the structures of the zeolite less than phosphoric acid. The results also indicate that (NH//4)//2HPO//4, NH//4H//2PO//4, and (NH// 4)//3PO//4 have similar inhibition effect. The order of adding phosphorus also affects the formation of the spinel. The appropriate ratio of the phosphorus (in the form of H//3PO//4) to zeolite for proper acidity of the catalyst has been found to be 0. 1.