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