Qualifying original journal studies (8)
Relevance-selected, not bibliometrically ranked. Citations are verified against Crossref; scientific details are restricted to the accessible indexed or abstract-level evidence stated in each entry.
1. Highly-efficient and magnetically-separable ZnO/Co@N-CNTs catalyst for hydrodeoxygenation of lignin and its derived species under mild conditions
Virendra Ranaware, Deepak Verma, Rizki Insyani, Asim Riaz, Seung Min Kim, Jaehoon Kim (2019). Green Chemistry. DOI: 10.1039/C8GC03623C
Class: H₂-HDO / lignin valorization
Substrate: Lignin and derived species; vanillin is an explicitly exposed example.
ZnO role and phase: ZnO and Co on N-doped carbon nanotubes; multicomponent catalyst, not ZnO alone. The paper describes amorphous ZnO and crystalline Co; in-use state requires fuller verification.
Evidence and interpretation: The study calls the process HDO. Its highlighted vanillin-to-creosol result removes the aldehyde oxygen but retains phenolic oxygen; it is not complete deoxygenation.
Access: Publisher abstract / indexed publisher content; full text not inspected. Evidence record
2. High-Yield Production of Deoxygenated Monomers from Kraft Lignin over ZnO-Co/N-CNTs in Water
Umair Mushtaq, Jaeyong Park, Asim Riaz, Virendra Ranaware, Muhammad Kashif Khan, Deepak Verma, Jaehoon Kim (2021). ACS Sustainable Chemistry & Engineering. DOI: 10.1021/acssuschemeng.0c08664
Class: H₂-HDO / lignin valorization
Substrate: Kraft lignin.
ZnO role and phase: ZnO–Co on N-doped carbon nanotubes; ZnO is a component of a multicomponent formulation. Operating-phase evolution is not established here.
Evidence and interpretation: Deoxygenated lignin-derived monomers; lignin depolymerization and deoxygenation are intertwined, not a single-substrate pathway test.
Access: Publisher abstract / indexed record; full text and SI not inspected. Evidence record
3. A Cu-ZnO-Al2O3 catalyst with oxygen vacancy for efficient hydrodeoxygenation of lignin-derived guaiacol to hydrocarbons
Yong Liu, Xinghua Zhang, Lungang Chen, Jianguo Liu, Qi Zhang, Longlong Ma (2024). Chemical Engineering Science. DOI: 10.1016/j.ces.2023.119616
Class: H₂-HDO
Substrate: Guaiacol.
ZnO role and phase: Cu–ZnO–Al₂O₃ mixed catalyst; reported ZnO surface oxygen vacancies. Active-state speciation and ZnO-only contribution require checking the full paper.
Evidence and interpretation: Guaiacol HDO to hydrocarbons; conversion and product yields should not be conflated.
Access: Publisher/indexed abstract; full text not inspected. Evidence record
4. On the reduction of CO 2 footprint via selective hydrodeoxygenation by ZnO–Ti 3 C 2 T x catalyst under solvent-free conditions
Bhagirath Saini, R. Krishnapriya, Meena Yadav, Rahul Singhal, Rakesh K. Sharma (2023). Green Chemistry. DOI: 10.1039/D3GC01260C
Class: H₂-HDO
Substrate: Methyl oleate.
ZnO role and phase: ZnO–Ti₃C₂Tₓ composite; ZnO oxide component. Working-state characterization not independently assessed.
Evidence and interpretation: The authors report selective conversion to n-C18, consistent with a carbon-retaining HDO route; comparative carbon and oxygen balances require full text.
Access: Publisher abstract; full text and SI not inspected. Evidence record
5. Highly Selective Hydrodecarbonylation of Oleic Acid into n ‐Heptadecane over a Supported Nickel/Zinc Oxide–Alumina Catalyst
Guangci Li, Feng Zhang, Lei Chen, Chuanhui Zhang, He Huang, Xuebing Li (2015). ChemCatChem. DOI: 10.1002/cctc.201500418
Class: Hydrodecarbonylation
Substrate: Oleic acid.
ZnO role and phase: Ni on zinc oxide–alumina support; ZnO is a support component, not the only active material. Operating phase not independently checked.
Evidence and interpretation: Hydrodecarbonylation produces n-heptadecane: loss of a carbon atom distinguishes this from carbon-retaining fatty-acid HDO.
Access: Publisher bibliographic and abstract record; full text not inspected. Evidence record
6. Effect of Zn/Al ratio of Ni/ZnO-Al2O3 catalysts on the catalytic deoxygenation of oleic acid into alkane
Lei Chen, Feng Zhang, Guangci Li, Xuebing Li (2017). Applied Catalysis A: General. DOI: 10.1016/j.apcata.2016.11.012
Class: Catalytic deoxygenation
Substrate: Oleic acid.
ZnO role and phase: Ni/ZnO–Al₂O₃; mixed-oxide support composition varied. ZnO is a support constituent; reduced catalyst state requires full-text verification.
Evidence and interpretation: Alkane production and deoxygenation; mechanism and H₂ basis not independently established here, so do not relabel as pure HDO.
Access: Institutional/indexed abstract; full text not inspected. Evidence record
7. Sustainable hydrocarbon fuels via “one-pot” catalytic deoxygenation of waste cooking oil using inexpensive, unsupported metal oxide catalysts
Ağah Yıldız, Jillian L. Goldfarb, Selim Ceylan (2020). Fuel. DOI: 10.1016/j.fuel.2019.116750
Class: Deoxygenation without added H₂
Substrate: Waste cooking oil.
ZnO role and phase: Unsupported ZnO was among the metal oxides compared; post-reaction phase not verified.
Evidence and interpretation: One-pot catalytic deoxygenation; published comparison includes thermal effects. Catalyst-specific oxygen balance and product pathways need full-text checking.
Access: Institutional abstract / indexed record; full text not inspected. Evidence record
8. The role of oxygen vacancies in biomass deoxygenation by reducible zinc/zinc oxide catalysts
Xiao Xiao, Helen Bergstrom, Ryan Saenger, Benjamin Johnson, Runcang Sun, Andrew Peterson (2018). Catalysis Science & Technology. DOI: 10.1039/C7CY02535A
Class: Biomass oxygenate deoxygenation
Substrate: Biomass-derived oxygenates; specific tested molecules not verified in the accessible record.
ZnO role and phase: Reducible zinc/zinc oxide catalyst system; metallic Zn, ZnO and vacancy-containing states must not be assumed interchangeable.
Evidence and interpretation: Study concerns oxygen-vacancy effects in biomass deoxygenation; exact pathway and gas basis must be checked before labeling it H₂-HDO.
Access: Publisher / scholarly abstract record; full text not inspected. Evidence record
Search and evidence limitations
OpenAlex was searched first for direct lignin and phenolic leads; a separate OpenAlex connector was unavailable, so the two research workstreams had unequal access. Crossref DOI metadata, publisher and institutional records, citation links and broader web-indexed records were also searched. Search families included ZnO, zinc oxide, Zn–Al and Zn–Co mixed oxides with hydrodeoxygenation, deoxygenation, hydrodecarbonylation, guaiacol, lignin, oleic acid, methyl oleate, waste cooking oil and biomass vapours. Search date: 2 November 2026.
The earlier 37-record report was consulted as a lead, not counted wholesale. This is a fresh scope, but papers may overlap the earlier report; a complete paper-by-paper overlap audit was not finished. DOI deduplication applies within this report. Bibliographic metadata were rechecked programmatically against Crossref. The classification and ZnO role are based on title, abstract or accessible indexed records, not a complete independent full-text and supporting-information review. The abstract-only evidence, missing full-text characterization and incomplete citation chasing limit confidence and completeness. This should not be used as a publication-ready systematic review or a claim that no additional studies exist.
Important future work: retrieve the original full texts and SI; establish ZnO at preparation and during operation; screen citation networks and non-title mentions; audit the previous report DOI by DOI; and expand to the approximately 40 genuinely qualifying studies sought.