Presidential Green Chemistry Challenge: 2003 Greener Synthetic Pathways Award
Süd-Chemie Inc. (now a Clariant Group Company)
A Wastewater-Free Process for Synthesis of Solid Oxide Catalysts
Innovation and Benefits: Süd-Chemie's new process to synthesize solid oxide catalysts used in producing hydrogen and clean fuel has virtually zero wastewater discharge, zero nitrate discharge, and no or little NOX emissions. Each 10 million pounds of oxide catalyst produced by the new pathway eliminates approximately 760 million pounds of wastewater discharges, 29 million pounds of nitrate discharges, and 7.6 million pounds of NOX emissions. The process also saves water and energy.
Summary of Technology: Some major achievements in pollution reduction have been made recently through advancement of catalytic technologies. One such effort is in the area of hydrogen and clean fuel production. However, the synthesis of catalysts for such reactions is often accompanied by the discharge of large amounts of wastewater and other pollutants, such as NOX, SOX, and halogens.
As a result of their commitment to continuously develop and invest in new and improved catalyst synthesis technologies, Süd-Chemie successfully developed and demonstrated a new synthetic pathway that is able to achieve virtually zero wastewater discharge, zero nitrate discharge, and no or little NOX emissions. Meantime, it substantially reduces the consumption of water and energy. For example, it is estimated that about 760 million pounds of wastewater discharges, about 29 million pounds of nitrate discharges, and about 7.6 million pounds of NOX emissions can be eliminated for every 10 million pounds of oxide catalyst produced.
The new synthetic pathway is based on very simple chemistry. Instead of acid-base precipitation typically using metal nitrate as raw material, the new process starts with a clean metal that is readily and economically available in commercial quantities. The synthesis proceeds by reaction of the metal with a mild organic acid in the presence of an oxidation agent. The function of the acid is to activate the metal and extract electrons to form the oxide precursor. With assistance of the oxidation agent (typically air), a porous solid oxide is synthesized in one step at ambient temperature without any wastewater discharge. The other active ingredients of the catalyst can be incorporated using the concept of wet-agglomeration. In contrast, the precipitation process requires intensive washing and filtration to remove nitrate and the other salts. Further, the new process substantially reduces the consumption of water and energy for production of solid oxide catalysts over conventional methods. The emission in the entire process is only pure water vapor and a small amount of CO2 that is generated during spray-drying and afterburning of hydrogen.
This wastewater-free process for making solid oxide catalysts has been demonstrated, and more than 300 kilograms of the metal oxide catalysts have been produced. Patent protection is being sought for the development. The catalysts made by the green process give superior performance in the synthesis of clean fuels and chemicals. The market for such solid oxide catalysts is estimated to be approximately $100 million. Süd-Chemie is the first in the industry to use the green process for making a catalyst for the synthesis of "green" fuels and chemicals.