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Spent hydrocracking catalyst secondary resource

Used refinery catalyst from hydrocracking, which combines cracking and hydrogenation of hydrocarbon feeds. This secondary-resource class is distinct from spent fluid catalytic cracking catalyst, automotive catalyst and the broader category of all hydroprocessing catalysts. The selected Thai refinery material was decoked before laboratory leaching; its composition is not a universal catalyst formulation, and no constituent-element criticality is inherited.

Microbial & Biochemical Mechanisms (1)

Metal mobilization with pretreated Aspergillus aculeatus culture filtrate

bioleaching Microbial

Associated Organisms: Aspergillus aculeatus (NCBITaxon:5053)

A culture filtrate from a Thai soil isolate reported as Aspergillus aculeatus was associated with measurable metal release from decoked spent hydrocracking catalyst. The filtrate was subsequently pH-adjusted and autoclaved; live cells did not act during leaching. Source inconsistencies constrain quantitative and molecular interpretation, so the accepted claim is qualified laboratory mobilization, not a validated optimal yield or industrial process.

Experimental Context & Analytical Limits:
NICS Innovation Company supplied used catalyst from refineries in Thailand's Eastern Economic Corridor. Material was heated at 600 degrees C for six hours, powdered and sieved below 150 micrometres. A Phichit gold-mine-soil isolate selected for growth on catalyst-containing agar was identified morphologically and by reported 100% sequence identity to reference NR_111412.1; the isolate's own accession and culture-deposit ID are not supplied. Potato dextrose broth initially pH 6.5 was cultured for nine days at 30-35 degrees C, 150 rpm; mycelia were filtered out and broth centrifuged 10000 rpm for ten minutes. Methods then say pH 6.5 adjustment with 2 N HCl before autoclaving. A 250 mL flask held 100 mL filtrate plus catalyst for 180 minutes. Methods use 3, 6, 10% w/v pulp, 30-50 degrees C and 120-180 rpm; independent optimization trials used nominal 10% w/v, 50 degrees C and 148 rpm. Filtered liquid was analyzed by ICP-AES; trials were triplicated.
Curated Evidence Points:
Methods pp. 3-5 and Tables 5, 7 report release after fungal-filtrate contact and lower values in controls described as cell-free culture medium. Figure 1 documents citric/oxalic acid production and falling pH during prior culture growth. Table 7 clearly distinguishes model predictions from experimental values: for Mo, 24.55% predicted versus 22.95 +/-0.80% experimental. These are reported feed-normalized measurements, not accepted product-recovery yields; no downstream isolated product was measured.
Figure 1 shows final culture pH near 3.5, whereas methods say adjust the resulting filtrate to 6.5 using HCl. The direction and chemical treatment are unresolved. Tables 2, 5 label pulp density mg/L but methods/optimization text say %w/v; neither conversion nor corrected value is assumed. The stated control was at 180 rpm, unlike the 148 rpm optimized trial, and the relationship between that control and Table 7 controls is unclear. Control percentages on p. 8 (Al 0.05, Ni 0.08, Mo 0.03, Fe 0.03, Zn 0.02) differ from Table 7 (0.30, 0.35, 0.35, 0.32, 0.03). These ambiguities prevent treating this as a fully chemistry-matched demonstration of microbial enhancement.
The source acknowledges incomplete acid digestion of the pretreated catalyst used for the denominator, so normalized percentages need not represent true total-feed extraction. Model fit is not direct molecular evidence; Table 6 reports significant Al lack of fit (p=0.018), and no kinetic uncertainty estimates or before/after surface characterization were provided. Citric/oxalic acid detection during cultivation does not quantify their causal contribution after pH adjustment/autoclaving. Proposed surface-reaction control, enzyme pathways and environmental/economic superiority are not established independently; culture preparation plus 600-degree-C decoking also precede the short leach. No pilot or industrial deployment was tested.

Sources & References

  1. sawangchart_2026: Sawangchart, Meksiriporn and Sutjaritvorakul (2026). Process Optimization and Kinetics Study of Metals Leaching from Spent Hydrocracking Catalysts by Cell-free Medium Filtrate of Aspergillus aculeatus. Trends in Sciences 23(10):13063. Published 10 May 2026; DOI 10.48048/tis.2026.13063. Methods pp. 3-5, Tables 4-8, Figures 1-4.
    https://doi.org/10.48048/tis.2026.13063 (accessed 2026-10-11)
  2. ncbi_aculeatus: NCBI Taxonomy 5053: Aspergillus aculeatus, species; does not identify the experimental Thai isolate.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=5053 (accessed 2026-10-11)
  3. ncbi_reference_its: NCBI RefSeq NR_111412.1: Aspergillus aculeatus CBS 172.66 ITS region from type material; this is the reference matched by the paper, not its experimental isolate sequence.
    https://www.ncbi.nlm.nih.gov/nuccore/NR_111412.1 (accessed 2026-10-11)

Curation History

Timestamp Curator Action Summary
2026-10-11T09:26:04.479595+00:00 Codex (GPT-6; Codex) CREATE Created the distinct secondary-resource identity and source-scoped laboratory evidence, preserving control, measurement, scale and source-consistency limitations.

Record source: data/records/spent-hydrocracking-catalyst.yaml