Measuring TiCl4 and Vanadium in TiO2 Pigment Production

Application Summary

Analytes TiCl4 (titanium tetrachloride), Vanadium
Detector OMA-300 Process Analyzer
Process Stream TiCl4 feed gas; recycle gas
Typical Measurement Range 0-10,000 ppm

Introduction

Known in the paint industry as the “whitest white,” titanium dioxide is a pigment used worldwide. In the chloride production method, titanium ore is converted to TiCl4, from which metallic chloride impurities are discarded. Oxidation of purified TiCl4 yeilds bright, finish-ready TiO2.

There are 2 critical points of analysis in this production process:

  • (1) The incoming stream of TiCl4 needs to be pure to yeild high quality TiO2. This requires verification that the TiCl4 feed is free of incident vanadium.
  • (2) The waste/recycle gas stream should be free of TiCl4 if the process is running efficiently. The presence of TiCl4 at this stage indicates incomplete hydrolysis and waste of valuable raw materials.

The OMA system is the ideal instrument for both analysis points, as TiCl4 and vanadium each have distinct, strong absorbance curves in the UV wavelength range. Dispersive analysis is absolutely necessary; collateral data is needed to differentiate the absorbance of TiCl4 from the absorbance of chlorine in the gas stream.

Absorbance Spectrum of TiCl4 in Process Gas

The spectra below demonstrate the overlapping absorbance of the analyte (TiCl4) and background composition (Cl2), and the importance of a full-spectrum method. The ECLIPSE software in the OMA uses all of the measurement wavelengths (each diamond in the spectra below represents a single measurement wavelength) as data points to de-convolute the different chemicals’ absorbance curves.

Spectrum TiCl4 and Cl2

Absorbance Curve of Vanadium in a TiCl4 Background

The measurement wavelength range used for measuring vanadium concentration in this application is demonstrated below:

Spectra vanadium in TCl4 1 ppm

Sample Conditioner for Vanadium Measurement

The system below was built to measure 0-10 ppm vanadium impurity in a liquid TiCl4 stream:

SCS vanadium in titanium tetrachloride

Application Data

The specifications below represent performance of the OMA-300 Process Analyzer in a typical TiCl4 / vanadium application.

For technical details about the OMA-300 Process Analyzer, see the data sheet:
DS-001A: OMA-300 Process Analyzer

All performance specifications are subject to the assumption that the sample conditioning system and unit installation are approved by Applied Analytics. For any other arrangement, please inquire directly with Sales.

Performance Specifications
Accuracy Custom measurement ranges available; example ranges below.
TiCl4 0-2,000 ppm: ±15 ppm
0-10,000 ppm: ±1% full scale
Vanadium 0-5 ppm: ±0.3 ppm
Cl2 0-100 ppm: ±5 ppm
0-10,000 ppm: ±2% full scale or 5 ppm*
0-100%: ±2% full scale
*Whichever is larger.

Note: Subject to modifications. Specified product characteristics and technical data do not serve as guarantee declarations.

Further Reading