Environmental Engineering Reference
In-Depth Information
Figure 9.2: Radial distribution of vanadium for catalyst prepared (a) from spent catalyst A; (b)
from spent catalyst B [From ref.
9
. Reprinted with permission].
boehmite with the most fouled catalysts C having pore volume of 0.10 mL/g (
Table 9.1
). In
spite of this, an adequate pore volume could be achieved up to 40% of the spent catalyst. For
most mixtures in
Table 9.3
, pore volume in 100-300 A pores accounted for more that 80% of
the total pore volume.
Figure 9.3 [9]
shows the trends in surface area and pore volume of the
reprocessed catalysts versus the amount of spent catalyst C. It should be noted that the surface
area of the latter was 18 m
2
/g (
Table 9.1
), whereas the surface area of boehmite was 165 m
2
/g.
Again, an adequate surface area was maintained up to about 40 wt.% of the spent catalyst in
the reprocessed catalyst.
9.1.1.2 Testing of Reprocessed Catalysts
The reprocessed catalysts were tested for HDS and HDM of the atmospheric residue derived
from a Kuwaiti crude. In the feed and product steams, the contents of Ni, Mo, and V were
determined without ashing using the same instrumentation as used for catalysts. The analysis
of sulfur in liquid products and in the feed was performed using the Oxford Model 3000 XRF
analyses. The catalyst activity was determined in the high-pressure fixed-bed microreactor at
370 and 390
◦
C and
12 MPa of H
2
using the H
2
/feed ratio of 1000. The tests were of 100 h
duration. Prior to testing, the catalysts were presulfided in the 1 %CS
2
/gas oil mixture.
Properties of the Kuwait atmospheric residue used for testing are shown in
Table 9.4 [522]
.
∼
Figure 9.4 [522,523]
shows the effect of the amount of spent catalyst A added to boehmite on
HDS and hydrodevanadization (HDV) activity at 390
◦
C. For both functionalities, the activities
increased with the amount of catalyst added. Also, the activities were greater for decoked
catalyst. These trends were similar for the other catalysts. However, these trends do not reflect
accurately the effect of the amount of active metals added to boehmite. For example, based on
