Catalyst and process development for synthesis gas conversion to isobutylene. Quarterly report, July 1, 1992--September 30, 1992 Page: 4 of 36
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CA TAL YSTS SYNTHESIS
Zirconia has been prepared by precipitation with ammonium hydroxide or sodium
hydroxide from zirconyl nitrate, by a modified sol gel method , and by a
hydrothermal method. A catalyst with 2% Th on zirconia was prepared by
precipitating zirconia followed by impregnating with thorium nitrate, drying and
calcining at 500 *C for 5 hours. A 10% Th on zirconia was prepared by a
hydrothermal method. Zirconia was prepared with 1.6% Na by using sodium
hydroxide and ammonium hydroxide to precipitate zirconyl nitrate. Zirconia and
zirconia/silica with a molar ratio of 4 Zr:1 Si were prepared using the modified sol
gel procedure, and these catalysts gave a tetragonal XRD pattern after calcination
and after reaction. The 1.6%Na/10.3%Ti/ZrO2 (HT) had a cubic structure, and
the remaining catalysts were monoclinic after calcining them at 500 *C for 2.5
hours. Table 1 presents the characterization data obtained for the catalysts used
in this study.
EXPERIMENTAL UNITS USED FOR CA TAL YST EVAL UA TION
Two bench scale units with tubular reactors and on-line analysis were used for
evaluation of the catalysts. The data in Table 2 illustrates intra- and inter-
laboratory reproducibility for a zirconia catalyst prepared by precipitation using the
two reactor systems and data reported by Gajda et al. [121 of UOP. Essentially
the same results are obtained for each of the units and laboratories. This was
expected since the units use tubular reactors, but because of different ovens,
gc's, and reactor size and configuration the tests were conducted to insure intra-
and inter- laboratory reproducibility for our catalyst program. By comparing the
results with data reported by Gajda et al., inter-laboratory reproducibility is
illustrated. Since the catalyst used by Gajda et al. was prepared by precipitation
of zirconyl chloride, the results shows that catalysts of equal reactivity and
essentially the same selectivities are obtained for catalysts prepared by
precipitating zirconyl nitrate or zirconyl chloride. Because the two units yielded
the same results on the same catalyst no reference is made in the manuscript as
to which unit was used to collect the data.
RESUL TS AND DISCUSSION
Figure 1 shows a comparison at 400 C of catalytic activities. Zirconia, zirconia
with 1.6% sodium, and 3.2%Ti, 2%Th/ZrO2 were prepared by co-precipitation
of zirconyl nitrate with ammonium hydroxide. After calcination the first two
catalysts were monoclinic, while the 3.2%Ti,2%Th/ZrO2 gave a tetragonal
structure. Hydrothermal synthesis was used to prepare catalysts with 1.6 wt%
Na, 10.3% Ti/zirconia and 0.6%Na, 2%Ti, 2%Th/zirconia which had cubic and
tetragonal structures, respectively. The activities or the catalysts are ranked as
3.2% Ti, 2% Th/zirconia > 1.6% Na on zirconia > zirconia> 1.6% Na: 10.3%
Ti on zirconia. The product from the latter catalysts contains 31.2% i-C4s with
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Anthony, R.G. & Akgerman, A. Catalyst and process development for synthesis gas conversion to isobutylene. Quarterly report, July 1, 1992--September 30, 1992, report, November 13, 1992; United States. (digital.library.unt.edu/ark:/67531/metadc701999/m1/4/: accessed October 17, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.