TITLE: Low severity upgrading of F-T waxes with solid superacids. Quarterly report, December 1, 1992--February 28, 1993. AUTHOR: J. W. Tierney; I. Wender. INST. AUTHOR: Pittsburgh Univ., PA. Dept. of Chemical and Petroleum Engineering. SPONSOR: Department of Energy, Washington, DC. LANGUAGE: English PUB. TYPE: Technical Report PUB. COUNTRY: United States SOURCE: Department of Energy [DE], 26 Mar 93, 13p. NTIS ORDER NO.: DE93011453INW ABSTRACT: In the last quarters a new class of solid superacids, including sulfated zirconium-hafnium oxides and ZrO(sub 2)/SO(sub 4) modified by Mn and Fe, were synthesized and shown to be active for isomerization and hydrocracking of hexadecane (n-C(sub 16)H(sub 34)). The reaction was carried out in a tubing bomb under mild conditions: 2.5 MPa and 433 K. Pt/HfO(sub 2)S0(sub 4) catalyst exhibited a low activity for hydrocracking of n-C(sub 16), but the addition of ZrO(sub 2) to the sulfated hafnium improved its activity considerably. An 85 wt % conversion level was achieved when the molar ratio of ZrO(sub 2) to HfO(sub 2) reached 1:1, indicating the possibility of a synergistic effect between zirconium and hafnium. It has recently been reported that Mn,Fe/ZrO(sub 2)/SO(sub 4) is about three orders of magnitude more active than ZrO(sub 2)/SO(sub 4) for isomerizing n-butane. As a result, an 0.5%Mn1.5%Fe/ZrO(sub 2)/SO(sub 4) catalyst was prepared according to a procedure given in a patent. It was found that, without Pt, the catalyst was inactive for hydrocracking of n-C(sub 16), possibly by deactivation due to coking. It is interesting that a 68 wt % conversion level was achieved after incorporation of Pt along with a product distribution that was shifted towards longer chain paraffins. ZrO(sub 2)/SO(sub 4)has been reported to be a superacid with H(sub 0) < (minus)16 as measured by the Hammett indicator method. However, the acid strength of some ZrO(sub 2)/SO(sub 4) based catalysts, such as the mentioned catalysts, could not be measured by using Hammett indicators because the catalysts are colored gray. We successfully modified an in situ FT-IR analytical system to characterize the acidity of these catalysts. We have applied the method using pyridine as adsorbate to demonstrate their acid strength. Preliminary results indicated a level of acidity of our catalysts which is consistent with their performance in hydrocracking of n-C(sub 16). REPORT NUMBER: DOE/PC/91304-T5 CONTRACT NUMBER: FG22-91PC91304 |