Environmental and Safety Aspects of Spent Hydroprocessing Catalysts - Spent Hydroprocessing Catalysts - page 114

Table 5.5: Analysis of Toxicity Characteristic Leaching Procedure (TCLP) leachates (ppm) of spent
catalysts and Environmental Protection Agency (EPA) regulatory levels [From ref. 337 . Reprinted
with permission].
Metal Catalyst 1 Catalyst 2 Catalyst 3 EPA regulatory levels

As 53

< 0.1 < 0.1

5

Ba < 0.1 < 0.1 nd 100

Cd nd < 0.1 0.1 1

Co 1 2 293 -

Cr < 0.1 < 0.1 nd 5

Fe 3 83 15 -

Pb 0.3 0.3 0.4 5

Hg nd nd nd 0 . 2

Mo 249 9 310 -

Ni 657 455 4 -

Ag nd nd nd 5

Se < 0.1 < 0.1 nd 1

V < 0.1 205 < 0.1 -

Zn 0.2 < 0.1 0.3 -

5.2.2 Leachability

The methods, such as ASTD-3987 and the TCLP, are normally used to assess leachability of
the wastes dumped in landfills. The results in Table 5.5 are used as an example to illustrate the
hazardous nature of spent hydroprocessing catalysts [337] . The regulatory levels of trace
elements (last column in Table 5.5 ) and volatile organics are reported in Federal Register [16] ,
which has been issued and periodically updated by the US EPA. It should be noted that the
permitted levels of some of these metals in drinking water ( Table 5.1 ) are lower by a factor of
100 or more of the regulatory levels. Thus, these levels assume a dilution factor of 100 or more,
once the metal is leached out from the hazardous solid. For the analysis, catalysts were used
without decoking. The leachability of the catalysts was determined the TCLP procedure. The
method involves shaking catalyst particles in the solution of a buffer for 18 h. Subsequently,
solid particles and suspended fines were filtered off to obtain leachates for analysis. The test
simulates potential release of metals to the ground water during the contact with water.
Potential release of PAHs deserves attention as well. In this case, the same leachate that was
used for the determination of trace elements is being used. The set of analytical methods, used
for the PAHs analysis, is described in details in the EPA's Federal Register [16-18]
as well.

The catalyst 1 in Table 5.6 [337] was the extrudate form of the NiMo/Al 2 O 3 catalyst used for
hydroprocessing a distillate from primary upgrading of a heavy feed. The chestnut bur form of