Research leads triaged
Discovery Pipeline
Catalyst + Co-feed Pipeline
The next materials, catalysts, co-feeds, and product-slate choices to model before expanding the sewage-to-fuel bench program.
Materials or molecules to model
Bench/model experiments queued
Docker-selected catalyst discovery candidates
circular catalyst
NiO on sludge hydrochar loop
Test whether HTL solids can become a useful catalyst support instead of only a residual burden.
Measure Ni leaching, hydrochar surface area, ash poisoning, repeat-cycle activity, and spent-material routing.
- Catalyst
- NiO/HC from sludge-derived hydrochar
- Conditions
- 330 C / 120 bar
- H2 burden
- 25
- Readiness
- 52
Pyomo-formulated catalyst portfolio selector with deterministic enumeration, category coverage, HDN, stability, and hydrogen-burden constraints. Current package covers 7 categories and 11 molecular stress markers.
Molecular stress markers
Palmitic acid; Phenol; Ammonia; Chloride
Catalyst ranking is tied to specific N, O, S, chloride, coke, aqueous, and hydrogen markers so catalyst promise does not hide downstream fuel-release burden.
- Top marker
- Carbazole
- Experiment
- CuSO4, TiO2, and NiO/HC partition run
The leading candidates are still experiment packages: mild stabilization, deep HDN, zeolite cracking, circular hydrochar support, co-processing kinetics, and spent-catalyst forensics have to be measured together.
Decision stance
Model catalysts as penalties and opportunities, not magic yield multipliers
The best new direction is a measured catalyst/co-feed matrix: NiO on recycled hydrochar, ZSM-5 aqueous-phase upgrading, algae or food-waste co-feeds, and product-slate severity. Each case must carry its own hydrogen, catalyst-life, aqueous toxicity, metals, and residual-handling burden.
Generated catalyst package
Seven selected candidates that should be tested as a linked upgrading portfolio
NiO on sludge hydrochar loop
Score 52.6; O removal 58; N removal 32; stability 48; readiness 52. Measure Ni leaching, hydrochar surface area, ash poisoning, repeat-cycle activity, and spent-material routing.
Dual-base modified ZSM-5 upgrading
Score 59.2; O removal 75; N removal 40; stability 58; readiness 52. Prove nitrogen removal, coking, pore stability, metals/chloride tolerance, and catalyst regeneration.
TiO2 primary-sludge HTL benchmark
Score 48.8; O removal 50; N removal 28; stability 58; readiness 62. Measure catalyst recovery, ash interaction, biochar partitioning, oil fraction, and aqueous organic load.
Mild NiMo stabilization window
Score 65.3; O removal 51; N removal 25; stability 94; readiness 84. Confirm TAN, MCR, simdist, pressure drop, chlorine removal, and N-family shifts on project-specific biocrude.
Two-stage NiMo deep HDN/HDO
Score 74.7; O removal 90; N removal 88; stability 66; readiness 62. Measure hydrogen uptake, HDN kinetics, liquid-yield loss, coke, spent catalyst metals, and product properties.
Kinetic VGO co-processing gate
Score 75.7; O removal 86; N removal 78; stability 76; readiness 70. Validate blend ratio, miscibility, reactor response, hydrogen uptake, refinery catalyst limits, and product split.
Spent-catalyst forensics and guard-bed assay
Score 65.5; O removal 35; N removal 55; stability 90; readiness 78. Run ICP, SEM/EDS, coke, chloride, phosphorus, sulfur, nitrogen-family, and pressure-drop diagnostics.
Catalyst/material · 2025
Bench nextNiO on recycled hydrochar makes a circular catalyst loop testable
NiO/HC catalyst from calcined sludge HTL hydrochar
A 2025 catalytic HTL study used NiO loaded on sludge-derived hydrochar and reported biocrude yield up to 17.93 wt% plus a high-quality case with 39.40 MJ/kg HHV and 50.91% energy recovery.
- Plan impact
- This is the most practical catalyst lead because it reuses the solid HTL residue as a support instead of importing only fresh catalyst.
- Programmatic check
- Model nickel oxide loading, surface-area sensitivity, catalyst mass per dry ton, and a hydrochar recycle loop in the process ledger.
- Risk gate
- Do not promote until nickel leaching, ash accumulation, spent catalyst handling, and repeat-cycle activity are measured.
Aqueous phase · 2026
Model nowZSM-5 can turn some HTL aqueous carbon into supplemental oil, but pyridines remain
Silica-bound ZSM-5 supercritical aqueous-phase upgrading
A 2026 Frontiers topic summary reports ZSM-5 supercritical upgrading of HTL aqueous phase with 64-73% aqueous carbon reduction, supplemental biocrude production, aromatics such as phenol and 2-pentanone, and remaining nitrogen concentrated as pyridines.
- Plan impact
- Aqueous phase cannot stay a waste afterthought; it may be both a treatment liability and a secondary oil-yield opportunity.
- Programmatic check
- Add aqueous carbon-to-oil recovery, nitrogen speciation, COD reduction, and headworks recycle stress as explicit variables.
- Risk gate
- Full-scale return remains gated by nitrifier inhibition, UV disinfection interference, and treatment requirements.
Catalyst/material · 2026 online record
WatchDual-base modified ZSM-5 is a high-upside biocrude upgrading lead
NaOH + TPAOH modified ZSM-5 with mesopore creation
The reported sludge-biocrude upgrading record describes mixed-base ZSM-5 achieving 75.02% oxygen removal, 81.55% sulfur removal, 52.03 wt% upgraded yield, and more than 50 wt% hydrocarbons.
- Plan impact
- Hierarchical zeolite pores may solve part of the large-molecule access problem that limits conventional microporous cracking catalysts.
- Programmatic check
- Represent this as a high-severity catalytic upgrading scenario with oxygen, sulfur, hydrocarbon fraction, and coking risk fields.
- Risk gate
- Treat as a watch lead until catalyst lifetime, nitrogen removal, ash/metals poisoning, and hydrogen use are independently verified.
Co-feed · 2026
Bench nextWastewater-grown algae can become a site-grown co-feed rather than an external feedstock
Mixed algal-cyanobacterial biomass grown in municipal wastewater
A 2026 Scientific Reports HTL study of municipal wastewater-grown algae found a 42.93 MJ/kg biofuel sample with gasoline, kerosene, and diesel-range fractions under optimized conditions.
- Plan impact
- A wastewater-site algae loop could add lipid-rich carbon while recovering nutrients, but it adds land, light, harvesting, and seasonal variability constraints.
- Programmatic check
- Add algae productivity, harvesting energy, nitrogen/phosphorus uptake, oil fraction, and co-HTL yield response to the scenario model.
- Risk gate
- Only advance if the algae system improves the whole-site mass and energy balance after dewatering and harvesting penalties.
Hydrochar branch · 2026 online record
WatchAmino-acid deep eutectic solvent chemistry may upgrade sludge hydrochar
Arginine plus butyric acid DES-assisted HTC
A DES-assisted hydrothermal carbonization record used arginine and butyric acid, reporting a 21.9% increase in hydrochar carbon content and HHV improvement from 11.6 to 13.13 MJ/kg.
- Plan impact
- This is not the liquid-fuel answer, but it may improve residual handling, catalyst support quality, or a solid-fuel fallback.
- Programmatic check
- Model arginine/butyric acid make-up, solvent recovery, hydrochar carbon, HHV, and residual nutrient/metals routing.
- Risk gate
- Do not use it in the primary oil claim until solvent recovery, nitrogen doping, cost, and disposal outcomes are measured.
Upgrading strategy · 2026
Model nowWet-waste HTL can target marine fuel, renewable diesel, or SAF with different upgrading severity
Hydrotreating and hydrocracking product-slate control
A 2026 wet-waste HTL TEA/LCA model compared sludge, manure, and food waste across marine fuel, renewable diesel, and SAF cases, with modeled MFSP values near $2.58-$3.61/GGE when feedstock credits are included.
- Plan impact
- The business case should not lock onto one fuel too early; marine fuel may need less severe upgrading, while SAF requires deep nitrogen removal.
- Programmatic check
- Add a product-slate selector for marine, renewable diesel, and SAF with nitrogen target, hydrogen demand, carbon efficiency, and credit sensitivity.
- Risk gate
- Fuel-market choice remains gated by measured biocrude nitrogen, hydrotreating yield loss, CAP emissions, water demand, and policy credit durability.
Model next
Materials and molecules added to the research queue
NiO on recycled hydrochar
NiONickel(II) oxide
Active phase for the NiO/hydrochar catalytic HTL lead.
Model useCatalyst loading, nickel inventory, leaching risk, spent catalyst mass, and cost sensitivity.
Validation needMeasure nickel leaching, repeat-cycle activity, ash poisoning, and catalyst regeneration need.
NiO on recycled hydrochar and DES hydrochar
C/H/O/N/P/ash variableHydrochar support
Recycled solid HTL residue support for catalyst preparation and possible residual energy product.
Model useSupport yield, carbon content, surface-area proxy, ash/metals sink, and phosphorus route.
Validation needMeasure BET surface area, ash, metals, phosphorus speciation, HHV, and leachability.
ZSM-5 aqueous upgrading and dual-base ZSM-5
Al-Si-O frameworkZSM-5 zeolite
Cracking/upgrading catalyst for biocrude or HTL aqueous-phase carbon recovery.
Model useAromatic formation, hydrocarbon fraction, pore-access assumption, coke risk, and catalyst lifetime.
Validation needMeasure coke, pore collapse, metals poisoning, nitrogen fate, and product distribution.
Dual-base modified ZSM-5
NaOHSodium hydroxide
Inorganic base for hierarchical ZSM-5 desilication in the dual-base catalyst lead.
Model useCatalyst preparation material, washing burden, alkalinity, and waste salt route.
Validation needTrack sodium residuals, washwater load, zeolite crystallinity, and catalyst acidity.
Dual-base modified ZSM-5
C12H29NOTetrapropylammonium hydroxide
Organic base paired with NaOH in the mixed-base ZSM-5 modification lead.
Model useOrganic base consumption, catalyst synthesis cost, pore formation, and residual nitrogen risk.
Validation needMeasure material recovery or destruction, catalyst reproducibility, and synthesis emissions.
Amino-acid deep eutectic solvent chemistry
C6H14N4O2Arginine
Amino-acid component in the DES-assisted hydrochar branch.
Model useSolvent make-up, nitrogen-doping potential, solvent recovery, and hydrochar functionality.
Validation needMeasure solvent loss, nitrogen form in hydrochar, aqueous nitrogen, and cost per dry ton.
Amino-acid deep eutectic solvent chemistry
C4H8O2Butyric acid
Organic-acid DES component and dehydration/decarboxylation promoter in the hydrochar branch.
Model useAcid load, solvent recovery, volatile acid loss, and hydrochar oxygen reduction.
Validation needMeasure pH, volatile losses, aqueous COD, solvent carryover, and corrosion risk.
ZSM-5 aqueous upgrading and HTL-aq downstream impact
C4H4N2Pyrazine
Aqueous nitrogen heterocycle associated with nitrifier inhibition risk.
Model useNitrifier toxicity marker, nitrogen speciation, and return-stream inhibition proxy.
Validation needMeasure concentration before recycle and compare against nitrification inhibition tests.
Bench matrix
Experiments required before promoting these leads
NiO/hydrochar catalyst loop
Determine whether sludge-derived hydrochar can serve as a reusable catalyst support for HTL.
NiO loadingHydrochar calcination temperatureCatalyst wt%Reaction temperatureCycle count
MeasurementsBiocrude yield, HHV, Nickel leaching, Ash/metals, Surface area, Repeat-cycle activity
Stop conditionStop if nickel leaching, ash poisoning, or spent-catalyst disposal eliminates the yield benefit.
Aqueous-phase ZSM-5 recovery
Test whether HTL aqueous carbon can be reduced while producing supplemental oil without harming headworks biology.
ZSM-5 loadingSupercritical severityAqueous phase dilutionRecycle fraction
MeasurementsCOD reduction, Oil carbon yield, Pyridines, Phenolics, Nitrification inhibition, UV absorbance
Stop conditionStop if treatment burden or nitrifier inhibition is worse than direct aqueous polishing.
Co-feed algae and food-waste comparison
Compare site-grown algae, food waste, and FOG-rich co-feeds under the same HTL and upgrading ledger.
Co-feed ratioMoistureLipid fractionSolids loadingResidence time
MeasurementsBiocrude yield, Fuel fraction, Hydrogen demand, Harvesting/dewatering energy, Aqueous COD, N/P recovery
Stop conditionStop any co-feed case that improves reactor yield but loses on whole-site energy or residuals.
Product-slate severity selector
Map whether the realistic product should be marine fuel, renewable diesel, or SAF for each biocrude quality.
Nitrogen targetHydrogen pressureHydrocracking severityDistillation cutPolicy credit case
MeasurementsN ppm, O wt%, Hydrogen uptake, Fuel yield, MFSP, GHG and CAP emissions
Stop conditionStop SAF framing if deep denitrogenation destroys yield or requires uncompetitive hydrogen input.
Docker-selected experiments
The generated simulation turns catalyst leads into measurable release gates
240 C stabilization boundary run
Run staged NiMo tests at 200, 220, 240, 260, and 280 C with SFC-HRMS and simdist.
Find the highest stability gain that avoids oligomerization and protects the deep HDN bed.
Deep HDN yield-loss and hydrogen assay
Measure HDN, HDO, liquid yield, gas make, coke, hydrogen uptake, and nitrogen-family depletion.
Separates diesel-relevant upgrading from a mild stabilization claim.
Spent-catalyst autopsy and guard-bed release
Use ICP, SEM/EDS, coke, halide, phosphorus, sulfur, and HRMS inlet/outlet forensics.
Turns catalyst deactivation into a measured gate before pilot exposure.
CuSO4, TiO2, and NiO/HC partition run
Compare catalyst recovery, oil/asphaltene split, aqueous COD, metals, biochar ash, and leachability.
Keeps yield-positive catalyst tests tied to residual and aqueous penalties.
Dual-base ZSM-5 coking and metals test
Stress modified zeolite with real biocrude, ash/metals spike, chloride spike, and regeneration cycles.
Decides whether strong deoxygenation is durable enough to enter the bench package.
Model-component co-processing calibration
Fit representative N/O/S/aromatic markers against real sludge-biocrude and VGO blend data.
Determines whether refinery co-processing is a real option or a deferred scenario.
Source-backed simulation
a catalyst lead should not be promoted until heteroatom removal, hydrogen demand, catalyst life, metals/chloride tolerance, and spent-catalyst fate are measured together
catdisc-dual-base-zsm5-2026
SourceEfficient catalytic upgrading of municipal sludge hydrothermal biocrude via dual-base modified ZSM-5
2026 Fuel article reporting NaOH plus TPAOH modified ZSM-5 with strong deoxygenation and heavy-oil cracking signals.
Open sourcecatdisc-mild-hydrotreating-2026
SourceMild hydrotreatment as a stabilization step for nitrogen-rich sewage sludge biocrude
Open-access 2026 pilot trickle-bed work defining a mild NiMo stabilization window below 240 C and 1010 h operation.
Open sourcecatdisc-primary-sludge-catalysts-2024
SourceInfluence of catalysts on the hydrothermal liquefaction of municipal primary sludge
Open-access 2024 Fuel study comparing homogeneous and heterogeneous catalysts including CuSO4 and TiO2 for primary-sludge HTL.
Open sourcecatdisc-kinetic-coprocessing-2026
SourceKinetic modeling of HTL biocrude hydrotreating for stand-alone reactors and co-processing with vacuum gas oil
2026 kinetic and reactor-modeling work using 40+ representative biocrude model components and continuous-reactor validation.
Open sourcecatdisc-nio-hydrochar-2025
SourceCharacterization of biocrude oil from catalytic HTL of municipal sewage sludge with a Ni-based hydrochar
2025 sludge-derived hydrochar support lead for circular NiO/HC catalytic HTL testing.
Open sourcecatdisc-two-stage-hdt-2020
SourceTwo-stage catalytic hydrotreatment of highly nitrogenous biocrude from continuous HTL
Two-stage hydrotreating precedent for reducing coke and improving heteroatom removal in nitrogen-rich HTL biocrudes.
Open sourcecatdisc-water-research-2026-review
SourceHydrothermal liquefaction of municipal sludge: Biocrude production and fuel quality upgrading
2026 review emphasizing catalyst innovation, upgrading gaps, byproduct use, and pilot-scale integration.
Open sourcecatdisc-pnnl-sot-2022
SourcePNNL-32731 hydrothermal liquefaction and upgrading state of technology
Wet-waste HTL state-of-technology context for deashing, solids, upgrading, and system-level validation.
Open source