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Title: The role of titanium-oxo clusters in the sulfate process for TiO2 production

Journal Article · · Dalton Transactions
DOI: https://doi.org/10.1039/c9dt01337g · OSTI ID:1547405

TiO2 is manufactured for white pigments, solar cells, self-cleaning surfaces and devices, and other photocatalytic applications. The industrial synthesis of TiO2 entails: (1) the dissolution of ilmenite ore (FeTiO3) in aqueous sulfuric acid which precipitates the Fe while retaining the Ti in solution, followed by (2) dilution or heating the Ti sulfate solution to precipitate the pure form of TiO2. The underlying chemistry of these processing steps remains poorly understood. Here we show that the dissolution of a simple TiIV-sulfate salt, representative of the industrial sulfate process for the production of TiO2, immediately self-assembles into a soluble Ti-octadecameric cluster, denoted as {Ti18}. We observed {Ti18} in solution by small-angle X-ray scattering and Ti extended X-ray absorption fine structure (Ti-EXAFS) analysis, and ultimately crystallized it for absolute identification. The {Ti18} metal-oxo cluster was previously reported as a polycation; but shown here, it can also be a polyanion, dependent on the number of sulfate ligands it carries. After immediate self-assembly, the {Ti18}-cluster persists until TiO2 precipitates, with no easily identified structural intermediates in the solution or solid state, despite the fact that the atomic arrangement of {Ti18} differs vastly from that of titania. The evolution from solution phase {Ti18} to precipitated TiO2 nanoparticles was detailed by X-ray scattering and Ti-EXAFS. Here, we offer a hypothesis for the key mechanism of complete separation of Fe from Ti in the industrial sulfate process. These findings also highlight the emerging importance of the unusual Ti(Ti)5 pentagonal building unit, featured in {Ti18} as well as other early d0 transition metal-oxo clusters including Nb, Mo and W. Finally, this study presents an example of crystal growth mechanisms in which the observed “pre-nucleation cluster” does not necessarily predicate the structure of the precipitated solid.

Research Organization:
Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division
Grant/Contract Number:
SC0010802
OSTI ID:
1547405
Alternate ID(s):
OSTI ID: 1530467
Journal Information:
Dalton Transactions, Vol. 48, Issue 29; ISSN 1477-9226
Publisher:
Royal Society of ChemistryCopyright Statement
Country of Publication:
United States
Language:
ENGLISH

References (56)

Particle Size, Shape and Activity for Photocatalysis on Titania Anatase Nanoparticles in Aqueous Surroundings journal October 2011
Valence Change Ability and Geometrical Occupation of Substitution Cations Determine the Pseudocapacitance of Spinel Ferrite XFe 2 O 4 (X = Mn, Co, Ni, Fe) journal June 2016
The Role of Bi 3+ in Promoting and Stabilizing Iron Oxo Clusters in Strong Acid journal April 2018
The crystal structure of zirconyl chloride octahydrate and zirconyl bromide octahydrate journal July 1956
Electrochemical Photolysis of Water at a Semiconductor Electrode journal July 1972
Mechanism and kinetics of titanium hydrolysis in concentrated titanyl sulfate solution based on infrared and Raman spectra journal September 2015
Novel Preparation of N-Doped SnO 2 Nanoparticles via Laser-Assisted Pyrolysis: Demonstration of Exceptional Lithium Storage Properties journal December 2016
Amphoteric Aqueous Hafnium Cluster Chemistry journal April 2016
Reaction Pathway to the Only Open-Shell Transition-Metal Keggin Ion without Organic Ligation: Reaction Pathway to the Only Open-Shell Transition-Metal Keggin Ion without Organic Ligation journal October 2018
Structure of the Complex Ion in Aqueous Solutions of Zirconyl and Hafnyl Oxyhalides journal July 1960
Characterization of Chemical Speciation of Titanyl Sulfate Solutions for Production of Titanium Dioxide Precipitates journal March 2009
Giant metal-oxide-based spheres and their topology: from pentagonal building blocks to keplerates and unusual spin systems journal November 2001
Aqueous formation and manipulation of the iron-oxo Keggin ion journal February 2015
Synthetic strategies, diverse structures and tuneable properties of polyoxo-titanium clusters journal January 2018
Aqueous Hafnium Sulfate Chemistry: Structures of Crystalline Precipitates journal September 2014
Crystal structure of a complex basic zirconium sulfate journal December 1987
A novel nonanuclear hafnium oxide–hydroxide–sulphate cluster crystallised from aqueous solution journal January 2014
Small Titanium Oxo Clusters: Primary Structures of Titanium(IV) in Water journal March 2016
Titanium-Oxide Host Clusters with Exchangeable Guests journal December 2017
Titanium Dioxide-Based Nanomaterials for Photocatalytic Fuel Generations journal May 2014
The chemistry of nucleation journal January 2016
Counteranion-Stabilized Titanium(IV) Isopolyoxocationic Clusters Isolated from Water journal April 2016
Structural absorption by barbule microstructures of super black bird of paradise feathers journal January 2018
Sol–gel reactions of titanium alkoxides and water: influence of pH and alkoxy group on cluster formation and properties of the resulting products journal December 2009
Hafnium Sulfate Prenucleation Clusters and the Hf 18 Polyoxometalate Red Herring journal March 2014
U(IV) Aqueous Speciation from the Monomer to UO 2 Nanoparticles: Two Levels of Control from Zwitterionic Glycine Ligands journal May 2017
Aqueous Bismuth Titanium-Oxo Sulfate Cluster Speciation and Crystallization journal November 2017
A literature review of titanium metallurgical processes journal July 2011
Water-Soluble Pentagonal-Prismatic Titanium-Oxo Clusters journal August 2016
Theoretical Studies on Anatase and Less Common TiO 2 Phases: Bulk, Surfaces, and Nanomaterials journal May 2014
On the Crystal Structure of Some Basic Aluminium Salts. journal January 1960
Hydrated Titanium Oxide. Thermal Precipitation from Titanium Sulfate Solutions. journal March 1933
Mini review on photocatalysis of titanium dioxide nanoparticles and their solar applications journal September 2013
Review of functional titanium oxides. I: TiO2 and its modifications journal September 2016
A comprehensive comparison of transition-metal and actinyl polyoxometalates journal January 2012
Large Aqueous Aluminum Hydroxide Molecules journal January 2006
Water-soluble titanium-oxides: Complexes, clusters and nanocrystals journal March 2019
Atomic-scale cation dynamics in a monolayer VO X /α-Fe 2 O 3 catalyst journal January 2015
Structural Characterization of Modular Supramolecular Architectures in Solution journal November 2004
Identification of Ti Clusters during Nucleation and Growth of Sol—Gel-Derived TiO 2 Nanoparticles journal August 2013
Structures of Hydrated Titanium and Vanadium Ions in Aqueous Solutions Studied by X-Ray Absorption Spectroscopy journal November 1990
Understanding TiO 2 Photocatalysis: Mechanisms and Materials journal May 2014
The Construction of High-Nuclearity Isopolyoxoniobates with Pentagonal Building Blocks: [HNb27O76]16− and [H10Nb31O93(CO3)]23− journal November 2009
Unprecedented and Differently Applicable Pentagonal Units in a Dynamic Library: A Keplerate of the Type {(W)W 5 } 12 {Mo 2 } 30 journal November 2008
Fullerene-like Polyoxotitanium Cage with High Solution Stability journal February 2016
Size tailoring of TiO2 anatase nanoparticles in aqueous medium and synthesis of nanocomposites. Characterization by Raman spectroscopy journal February 2003
Structure of a Hydrated Sulfonatotitanyl(IV) Complex in Aqueous Solution and the Dimethylsulfoxide Solvated Titanyl(IV) Ion in Solution and Solid State journal January 2017
Probing protein fine structures by wide angle solution X-ray scattering journal June 2000
Titanate and titania nanostructured materials for environmental and energy applications: a review journal January 2015
TiO 2 Photocatalysis: A Historical Overview and Future Prospects journal December 2005
Isomerism in Titanium-Oxo Clusters: Molecular Anatase Model with Atomic Structure and Improved Photocatalytic Activity journal December 2018
The Construction of High-Nuclearity Isopolyoxoniobates with Pentagonal Building Blocks: [HNb27O76]16− and [H10Nb31O93(CO3)]23− journal November 2009
Isomerism in Titanium-Oxo Clusters: Molecular Anatase Model with Atomic Structure and Improved Photocatalytic Activity journal December 2018
Amphoteric Aqueous Hafnium Cluster Chemistry journal April 2016
Aqueous Bismuth Titanium-Oxo Sulfate Cluster Speciation and Crystallization journal November 2017
Large Aqueous Aluminum Hydroxide Molecules journal March 2006

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