Spent hydrodesulfurization catalyst secondary resource
Used catalyst from hydrodesulfurization of petroleum feeds, represented here by a characterized raw catalyst from a Brazilian diesel-treatment unit. This process-defined secondary resource is distinct from spent fluid catalytic cracking and hydrocracking catalysts, from fresh catalyst formulations, and from its constituent elements. The selected material was described as CoMo on alumina, but its measured composition and microbial response do not define all spent HDS catalysts. No constituent-element criticality designation is inherited.
Microbial & Biochemical Mechanisms (1)
FG-01 culture-associated acid leaching of raw diesel HDS catalyst
bioleaching
Microbial
Associated Organisms:
Acidithiobacillus thiooxidans (NCBITaxon:930)
Acidithiobacillus thiooxidans FG-01 cultivation and previously grown culture medium were associated with Al, Mo and V mobilization from raw spent diesel HDS catalyst. Commercial sulfuric acid gave similar or greater release in relevant comparisons, limiting any claim of microbial enhancement. Direct culture and two-stage leaching are separate assay arms; neither established an isolated metal product or industrial operation.
Experimental Context & Analytical Limits:
Ferreira et al. (2017) obtained 200 kg of spent catalyst from a Brazilian heavy-oil refinery diesel-treatment unit and subsampled it; the leaching feed received no grinding, solvent washing or decoking. Analytical digestion and microscopy drying/coating are characterization steps, not leach pretreatments. FG-01 was reported as a uranium-mine isolate from Paraná, supplied by the State University of São Paulo; no accession verifying the exact strain is supplied. Four-day T&K preculture was at 30 +/-1 degrees C and 150 rpm; general assays used 500 mL flasks with 100 mL medium, nominal initial 10^5 cells/mL, initial pH 2 adjusted with sulfuric acid, 29 +/-1 degrees C and 150 rpm. One-stage experiments used 5 g/L catalyst with or without 10 g/L elemental sulfur; Table 2 labels incubation 30 degrees C and samples at days 1, 3 and 7. In two-stage assays, catalyst was added after growth without catalyst had generated reported acidity around 40 g/L as sulfuric acid; the resulting solution was diluted before 5-50 g/L catalyst additions. The 2017 paper does not describe removing cells before this second stage; filtration of 25 mL analytical aliquots through 0.22-micrometre membranes must not be interpreted as preparation of a cell-free lixiviant. AAS measured the filtered-liquid metals. At least three replicate flasks were sacrificed during monitoring. Autoclaved medium controls and commercial sulfuric-acid controls were included; Table 3 does not identify its endpoint time or final acid concentration explicitly.
Ferreira et al. (2017) obtained 200 kg of spent catalyst from a Brazilian heavy-oil refinery diesel-treatment unit and subsampled it; the leaching feed received no grinding, solvent washing or decoking. Analytical digestion and microscopy drying/coating are characterization steps, not leach pretreatments. FG-01 was reported as a uranium-mine isolate from Paraná, supplied by the State University of São Paulo; no accession verifying the exact strain is supplied. Four-day T&K preculture was at 30 +/-1 degrees C and 150 rpm; general assays used 500 mL flasks with 100 mL medium, nominal initial 10^5 cells/mL, initial pH 2 adjusted with sulfuric acid, 29 +/-1 degrees C and 150 rpm. One-stage experiments used 5 g/L catalyst with or without 10 g/L elemental sulfur; Table 2 labels incubation 30 degrees C and samples at days 1, 3 and 7. In two-stage assays, catalyst was added after growth without catalyst had generated reported acidity around 40 g/L as sulfuric acid; the resulting solution was diluted before 5-50 g/L catalyst additions. The 2017 paper does not describe removing cells before this second stage; filtration of 25 mL analytical aliquots through 0.22-micrometre membranes must not be interpreted as preparation of a cell-free lixiviant. AAS measured the filtered-liquid metals. At least three replicate flasks were sacrificed during monitoring. Autoclaved medium controls and commercial sulfuric-acid controls were included; Table 3 does not identify its endpoint time or final acid concentration explicitly.
Curated Evidence Points:
Support
Source:
ferreira_2017
Methods pp. 120-122 establish the diesel HDS origin, raw feed, strain provenance and separate culture/leach stages. Figures 1-3 show culture-associated acidification and sulfur-dependent activity. Table 2 reports seven-day Mo release of 39 +/-4% without added elemental sulfur and 37 +/-3% with it; Table 3 reports two-stage Mo release of 55 +/-6% at 5 g/L and 39 +/-3% at 50 g/L. These are the source’s mass-normalized leaching percentages based on feed composition and liquid analysis, not isolated-product yields. Table 3 reports low Co, Cu and Ni release rather than universal extraction of every catalyst metal.
Partial
Source:
ferreira_2017
Table 2 gives seven-day commercial-acid Mo release of 65 +/-5%, exceeding both culture arms, despite the text calling the processes equivalent. For two-stage Mo, Table 3 pairs 55 +/-6% biological versus 54 +/-4% chemical at 5 g/L, and 39 +/-3% versus 41 +/-4% at 50 g/L; corresponding entries share the source’s non-significance letters. Al and V also show acid-only comparability. Uninoculated medium metal release is stated as below 0.5% but underlying data are not shown; that medium control is distinct from the stronger commercial-acid comparison. No biosurfactant production was measured, no enzyme causality was established, and nominal acid matching does not prove identical full medium chemistry or pH trajectories.
Partial
Source:
ferreira_2017
Quantitative inconsistencies remain unresolved. At 50 g/L, Table 3 Al is 24 +/-2%, whereas the abstract gives 26%. The conclusion’s Ni below-5% statement conflicts with Table 2 day-seven 5 +/-2%. Figure 2 text describes 3.1 x 10^6 cells/mL as nearly unchanged although the caption specifies initial 10^5 cells/mL; Figure 3 starts nearer 10^6, preventing a confident shared inoculum/biomass trajectory. The p. 126 mass-recovery sentence reports 31.3 g/L Al, 54.6 g/L Mo and another 30.4 g/L Mo, incompatible with Table 1 feed contents at 50 g/L and with its own repeated analyte label. These numbers are not silently corrected or accepted as measured recovered concentrations. Missing Table 3 endpoint and final acid concentration prevent a fully specified optimum claim.
Partial
Source:
ferreira_2017
Table 4 and Figure 4 concern local surface EDS composition and morphology; they do not establish bulk mass balance, a named crystalline product, intracellular uptake, or organic deposition merely from increased oxygen signal. Table 1 feed digestion and filtered-liquid AAS do not provide an isolated-product recovery accounting. The source’s economic and environmental advantages are proposals, not a measured cost study or deployment evidence.
Context_only
Source:
ferreira_2015
This related same-group FG-01 diesel HDS paper is retained as context rather than independent replication or an additional accepted yield. Its 27.5 g/L, nominal 20 g/L sulfuric-acid, four-day protocol differs from the 2017 arms and reports chemical/biological comparability. The abstract gives about 65% Al and 25% Mo, whereas the body/conclusion give about 24-28% Al and 46% Mo. Methods say culture broth was filtered at 0.22 micrometres before leaching, but the SEM discussion assigns attached cells; the biomass state remains unresolved. Complete author-hosted text and figure captions were inspected, but full-resolution figures were not acquired in this curation. The two publications’ similar feed composition and shared strain do not establish independent feed batches.
Sources & References
-
ferreira_2017: Ferreira, Sérvulo, da Costa, Ferreira, Godoy and Oliveira (2017). Bioleaching of Metals from a Spent Diesel Hydrodesulfurization Catalyst Employing Acidithiobacillus thiooxidans FG-01. Brazilian Journal of Chemical Engineering 34(1):119-129. DOI 10.1590/0104-6632.20170341s20150208; methods pp. 120-122, Tables 1-4 and Figures 1-4.
https://doi.org/10.1590/0104-6632.20170341s20150208 (accessed 2026-10-11) -
ferreira_2015: Ferreira, Sérvulo, Ferreira and Oliveira. Assessment of Metal Recovery from Raw Spent Hydrodesulfurization Catalyst through Bioleaching and Chemical Leaching. Brazilian Journal of Petroleum and Gas 9(4):137-145, issue dated 2015; author-hosted metadata dated January 2016. DOI 10.5419/bjpg2015-0014. Related source with unresolved abstract/body and filtration/SEM inconsistencies.
https://doi.org/10.5419/bjpg2015-0014 (accessed 2026-10-11) -
ncbi_thiooxidans: NCBI Taxonomy 930: Acidithiobacillus thiooxidans, species; this identifier does not identify strain FG-01.
https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=930&mode=Info (accessed 2026-10-11)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-11T11:13:13.293796+00:00 |
Codex (GPT-6; Codex) | CREATE | Created the process-defined spent HDS secondary-resource record from full primary evidence, preserving acid-only comparisons, direct/two-stage distinctions, conflicting measurements and laboratory limits. |
Record source: data/records/spent-hydrodesulfurization-catalyst.yaml