# Titanosilicate

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A **titanosilicate**, also called **titanium silicate** or **silicotitanate**, is a [silicate mineral](/source/Silicate_mineral) where some portion of the [silicon](/source/Silicon) atoms have been replaced by [titanium(IV)](/source/Titanium) atoms. The term most commonly refers to the [zeolitic](/source/Zeolite) polymorph, also called titanium [silicalite](/source/Silicalite), which is a [heterogeneous catalyst](/source/Heterogeneous_catalyst) in [industrial chemistry](/source/Industrial_chemistry).

## Applications

Titanosilicate catalysts are commonly used in [oxidation reactions](/source/Oxidation_reaction) that employ [hydrogen peroxide](/source/Hydrogen_peroxide) as an [oxidant](/source/Oxidant). The production of [propylene oxide](/source/Propylene_oxide) by [epoxidation](/source/Epoxidation) of [propylene](/source/Propylene) is a major industrial application.[1] Epoxidation by H2O2 is considered a [greener](/source/Green_chemistry) alternative to epoxidation via [propylene chlorohydrin](/source/Propylene_chlorohydrin), but this reaction of H2O2 and propylene competes with many [side reactions](/source/Side_reaction). The formation of titanium [coordination complexes](/source/Coordination_complex) in the zeolite structure improves selectivity for the epoxide.[2]

## Synthesis

Titanosilicates can be prepared via [crystallisation](/source/Crystallisation) of [silica](/source/Silica) and [titanium dioxide](/source/Titanium_dioxide) with [quaternary ammonium cations](/source/Quaternary_ammonium_cation) as a structure-directing agent. The silica and titanium dioxide are provided by [hydrolysis](/source/Hydrolysis) of [tetraethyl orthosilicate](/source/Tetraethyl_orthosilicate) and [tetrabutyl orthotitanate](/source/Tetrabutyl_orthotitanate).[3]

## Structure

TS-1, the major industrial titanosilicate, has the MFI crystal structure seen in [ZSM-5](/source/ZSM-5), another significant synthetic zeolite. The titanium atoms are [tetrahedrally](/source/Tetrahedral) coordinated, unlike the [octahedral](/source/Octahedral) coordination found in the main polymorphs of [titanium(IV) oxide](/source/Titanium(IV)_oxide). Because of the relatively small amount of titanium in the relatively large structure, it is difficult to determine the exact locations of active sites; this is a major obstacle in understanding the [reaction mechanism](/source/Reaction_mechanism) of titanosilicate catalysis.[4]

Other titanosilicates have been produced in other zeolite structures, as well as related mesoporous materials such as Ti-[MCM-41](/source/MCM-41).[5]

## History

The first synthetic titanosilicate zeolite, TS-1, was patented by Taramasso et al. in 1983.[6] TS-1 was first used industrially by [EniChem](/source/Versalis) in 1986, for the [hydroxylation](/source/Hydroxylation) of [phenol](/source/Phenol). They would later expand its usage into the production of [cyclohexanone oxime](/source/Cyclohexanone_oxime). TS-1 as a catalyst for epoxidation of propylene was first deployed at industrial scale by [Dow Chemical](/source/Dow_Chemical) and [BASF](/source/BASF) in 2008.[7]

## References

1. Smeets, Valentin; Gaigneaux, Eric M.; Debecker, Damien P. (2022). "Titanosilicate Epoxidation Catalysts: A Review of Challenges and Opportunities". *ChemCatChem*. **14**. [doi:10.1002/cctc.202101132](https://doi.org/10.1002/cctc.202101132). [hdl:2078.1/257495](https://hdl.handle.net/2078.1/257495)

1. Yang, Jimei; Liu, Shuling; Liu, Yanyan; Zhou, Limin; Wen, Hao; Wei, Huijuan; Shen, Ruofan; Wu, Xianli; Jiang, Jianchun; Li, Baojun (2024). "Review and perspectives on TS-1 catalyzed propylene epoxidation". *iScience*. **27** (3). [Bibcode:2024iSci...27j9064Y](https://ui.adsabs.harvard.edu/abs/2024iSci...27j9064Y). [doi:10.1016/j.isci.2024.109064](https://doi.org/10.1016/j.isci.2024.109064). [PMC 10875142](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10875142). [PMID 38375219](https://pubmed.ncbi.nlm.nih.gov/38375219)

1. Bai, Risheng; Navarro, M. Teresa; Song, Yue; Zhang, Tianjun; Zou, Yongcun; Feng, Zhaochi; Zhang, Peng; Corma, Avelino; Yu, Jihong (2020). "Titanosilicate zeolite precursors for highly efficient oxidation reactions". *Chemical Science*. **11** (45): 12341–12349. [doi:10.1039/d0sc04603e](https://doi.org/10.1039/d0sc04603e). [PMC 8162463](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8162463). [PMID 34094443](https://pubmed.ncbi.nlm.nih.gov/34094443)

1. Rzepka, Przemyslaw; Signorile, Matteo; Huthwelker, Thomas; Checchia, Stefano; Rosso, Francesca; Bordiga, Silvia; Van Bokhoven, Jeroen A. (2024). "Quantitative localisation of titanium in the framework of titanium silicalite-1 using anomalous X-ray powder diffraction". *Nature Communications*. **15** (1): 7757. [Bibcode:2024NatCo..15.7757R](https://ui.adsabs.harvard.edu/abs/2024NatCo..15.7757R). [doi:10.1038/s41467-024-51788-7](https://doi.org/10.1038/s41467-024-51788-7). [PMC 11377426](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11377426). [PMID 39237487](https://pubmed.ncbi.nlm.nih.gov/39237487)

1. Peng, Rui; Zhao, Dan; Dimitrijevic, Nada M.; Rajh, Tijana; Koodali, Ranjit T. (2012). "Room Temperature Synthesis of Ti–MCM-48 and Ti–MCM-41 Mesoporous Materials and Their Performance on Photocatalytic Splitting of Water". *The Journal of Physical Chemistry C*. **116**: 1605–1613. [doi:10.1021/jp210448v](https://doi.org/10.1021/jp210448v)

1. "Preparation of porous crystalline synthetic material [*sic*] silicon and titanium oxides". No. 4410501.

1. Millini, Roberto; Bellussi, Giuseppe; Pollesel, Paolo; Rizzo, Caterina; Perego, Carlo (2022). "Beyond TS-1: Background and recent advances in the synthesis of Ti-containing zeolites". *Microporous and Mesoporous Materials*. **346**. [Bibcode:2022MicMM.34612286M](https://ui.adsabs.harvard.edu/abs/2022MicMM.34612286M). [doi:10.1016/j.micromeso.2022.112286](https://doi.org/10.1016/j.micromeso.2022.112286)

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Adapted from the Wikipedia article [Titanosilicate](https://en.wikipedia.org/wiki/Titanosilicate) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Titanosilicate?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.