Bismuth metal oxide pyrochlores as electrode materials for electrolytic ozone and perchlorate generation

a technology of ozone and perchlorate, which is applied in the direction of electrolysis components, instruments, optics, etc., can solve the problems of low process efficiency, low concentration of ozone in water, and increase power consumption, so as to achieve safe and effective replacement

Inactive Publication Date: 2011-09-22
CERAMTEC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0015]The present invention provides bismuth mixed metal oxide pyrochlore materials suitable as high current density electrodes for electrolytic ozone and perchlorate generation. The bismuth mixed metal oxide pyrochlore materials disclosed herein provide safe and effective replacement where lead dioxide electrodes are currently used for ozone and perchlorate generation.

Problems solved by technology

Also, due to low partial pressure of ozone in the gas phase and limited solubility of ozone in water, the concentration of ozone in water will be low using this method.
A disadvantage of this process is the high voltage of the reaction, which increases the power consumption.
Also, the efficiency of the process is low because oxygen evolution competes with ozone production as set forth in Equation (2) below.
However lead dioxide anode is not completely stable at high current densities (>1 A / cm2) required for ozone generation.
These additional steps make the process impractical.
However, Pt is not presently used in commercial ozonators because of its high cost and poor long term performance, i.e., ozone generation efficiency drops quickly compared to lead dioxide.
Pt and boron-doped diamond (BDD) can potentially be used but they do not provide long cycle life.

Method used

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  • Bismuth metal oxide pyrochlores as electrode materials for electrolytic ozone and perchlorate generation
  • Bismuth metal oxide pyrochlores as electrode materials for electrolytic ozone and perchlorate generation
  • Bismuth metal oxide pyrochlores as electrode materials for electrolytic ozone and perchlorate generation

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example 1

[0052]Synthesis of Bi2Ru2O7. Stochiometric amounts of Bi2O3 and RuO2.xH2O (the concentration of RuO2 and H2O were determined by thermal gravimetric analysis (TGA) to be 76% and 24% respectively) were made into slurry by adding water and mixing with mortar and pestle. After mixing for 15 minutes, a consistent slurry was formed. The slurry was then dried in a drying oven and again mixed with pestle before heating at 650° C. for 24 hours followed by 750° C. for 24 hours. X-ray diffraction (XRD) was performed at each stage to determine the phase purity of the product. The XRD results are shown in FIG. 1. XRD data after the 750° C. step matched well with the Joint Committee on Powder Diffraction Standards (JCPDS) reference pattern with Bi2Ru2O7.3 except for 2 peaks. These peaks could not be attributed to either of the starting materials Bi2O3 and RuO2. Additional heating at 750° C. for another 24 hours did not change the intensity of the two peaks. Hence it was concluded that these peaks...

example 2

[0053]Rotating Ring Disk Electrode for Ozone analysis. A Rotating Ring Disk Electrode (RRDE) method was used to demonstrate that bismuth ruthenate can indeed function as an anode in electrolytic ozonator. A cross-sectional side view and bottom view of a typical RRDE device is shown in FIG. 2. The theory behind the application of RRDE for in-situ generation / detection of ozone is briefly as follows. The RRDE 100 consists of a central disk electrode 102 surrounded by a concentric ring electrode 104 with a thin Teflon U-cup insulator 106 separating them. The potential or the current at each electrode can be controlled independently using a bipotentiostat (not-shown). A bipotentiostat controls the voltage and measures the current at two working electrodes immersed in an electrolyte, using only one reference electrode and one counter electrode. The RRDE shown in FIG. 2 can be used to detect and measure O3 that is generated at the disk of RRDE. When the central disk electrode 102 is anodic...

example 3

[0057]Preparation of the Bi2Ru2O7 RRDE disk. The synthesized Bi2Ru2O7 product from Example 1 was mixed with aqueous suspension of polyvinyl alcohol binder to coat the particles with the binder. The Bi2Ru2O7 material and binder were pressed into pellets and fired at 1100° C. in air for 24 hours. The XRD pattern for the sintered material is shown in FIG. 3. The XRD pattern indicates that the crystal structure of the sintered material is quite different from the starting material. The identity of this material phase is not presently known. The final diameter of the pellets was ˜0.6 mm. The pellets were further ground to the size and shape of the RRDE disk for use in the RRDE setup. The surface of the disk was also polished to further smooth the surface. Conductive silver paint was applied on the back side of the disk and cured at 700° C. This was done to ensure good electrical contact between the metal spring of the RRDE and the mixed metal oxide disk. Scanning electron micrograph (SEM...

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Abstract

Novel bismuth based mixed metal oxide materials with pyrochlore structure are disclosed as anodes for electrolytic generation of ozone and perchlorate salts. These materials have high electrical conductivity and excellent stability in acidic electrolytes. These materials are more environmentally friendly than lead dioxide and less expensive than platinum.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims the benefit of U.S. Provisional Application No. 61 / 218,554, filed Jun. 19, 2009, entitled “Bismuth Metal Oxide Pyrochlores as Electrode Materials for Electrolytic Ozone and Perchlorate Generation,” the entire disclosure of which is hereby incorporated by reference.BACKGROUND OF THE INVENTION[0002]The present invention pertains to Bi-based mixed metal oxide anode materials with pyrochlore structure which are shown to be active as anode electrocatalyst materials for generating ozone and perchlorate. The invention further relates to an ozone or perchlorate generator for producing ozone through the electrolytic decomposition of water or oxidation of chloride salts.[0003]Ozonized water can be effectively used in the Medical, Food, Beverage and Agricultural (MFBA) industries as an antibacterial cleaning agent, as an oxidant and as pesticide. Ozone usage has recently been extended over to the semi-conductor industry for cl...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C25B11/04C25B1/13C25B9/00C25B1/26
CPCC25B11/04C25B1/13
Inventor BHAVARAJU, SAI
Owner CERAMTEC
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