Synthetic zeolites and other microporous oxide molecular sieves

Abstract

Use of synthetic zeolites and other microporous oxides since 1950 has improved insulated windows, automobile air-conditioning, refrigerators, air brakes on trucks, laundry detergents, etc. Their large internal pore volumes, molecular-size pores, regularity of crystal structures, and the diverse framework chemical compositions allow “tailoring” of structure and properties. Thus, highly active and selective catalysts as well as adsorbents and ion exchangers with high capacities and selectivities were developed. In the petroleum refining and petrochemical industries, zeolites have made possible cheaper and lead-free gasoline, higher performance and lower-cost synthetic fibers and plastics, and many improvements in process efficiency and quality and in performance. Zeolites also help protect the environment by improving energy efficiency, reducing automobile exhaust and other emissions, cleaning up hazardous wastes (including the Three Mile Island nuclear power plant and other radioactive wastes), and, as specially tailored desiccants, facilitating the substitution of new refrigerants for the ozone-depleting chlorofluorocarbons banned by the Montreal Protocol.

Use of Phosphate Waste as a Building Material

“…Although the zeolites minerals that form are not as ''stable'' as kaolinite, they are able to bond to each other and form a solid that is much more resistant to softening and deformation during annual wet/dry cycles. All zeolites are metastable to some degree (Sherman, 1999;Diop and Grutzeck, 2008). The ones that form first, in the presence of abundant water, will become less hydrated and undergo phase transitions as a result of diagenesis.…”

“…In the related aluminophosphates (AlPO 4 ), each negatively charged AlO 4 tetrahedron is balanced by a positively charged PO 4 tetrahedron, and non framework cations are not needed (Sherman, 1999). Still other variants include the silicoaluminophosphate (SAPO) structures in which Si substitutes some P in the AlPO 4 framework; each added Si needs a non framework cation to balance the charge on the framework.…”

Nanotechnologie: Eine neue soziale Dynamik an der Schnittstelle zwischen Wissenschaft und Öffentlichkeit

“…Jahrhundert systematisch untersucht und großindustriell umgesetzt, einschließlich beispielsweise der Verwendung synthetischer Zeolithe mit maßgeschneiderten Poren im Nanometerbereich seit den 1950er Jahren (Sherman 1999). Die Geschichte quantenchemischer Modellrechnungen begann in den 1920er Jahren und entwickelte sich seit Mitte des Jahrhunderts zusammen mit molekulardynamischen Simulationen weitgehend parallel zu den Verbesserungen der Computertechnik (Simões/Gavroglu 2001, Peyerimhoff 2002.…”

On the Novelty of Nanotechnology: A Philosophical Essay

“…Chemical catalysis has been systematically studied and industrially exploited since the early 20th century, including for instance the use of size-tailored nanoscale pores in engineered zeolites since the 1950s (Sherman 1999). The history of molecular modeling started in the first half of the 20th century and then largely developed along with improvements of computer technology.…”