A Multidecade Investigation of Silicoaluminophosphates in the Davis Lab: In Honor of Edith Flanigen

Mark E. Davis

California Institute of Technology

Beginning in the early1980s, my research efforts were influenced by Edith Flanigen. She and her co-workers invented the class of phosphate-based, crystalline molecular sieves [1,2]. My work on zeolites with the FAU topology that encapsulated rhodium complexes for hydroformylation initially brought me to interact with Edith; I spoke with her about the SAPO analogue, SAPO-37. I first synthesized this material from her suggestions about which examples to follow from their patent [3]. From that point, my students and co-workers and I embarked on a multidecade investigation into the synthesis, characterization and catalytic properties of phosphate-based, crystalline microporous solids.

I first presented our work on SAPOs (atomic arrangements in these materials) at the 1987 British Zeolite Association meeting where Edith was in the audience. In 2014, I was able to honor Edith by being the Edith M. Flanigen Honeywell UOP Invited Lecturer. Here, I will recap my multidecade efforts to synthesize phosphate-based, crystalline materials to honor Edith for her influence on me as well as many others in our field. I will discuss our efforts to elucidate the possible atomic arrangements in SAPOs [4], the discovery of the first extra-large pore material (VPI-5[5]) and reaction results demonstrating the positives and the limitations of SAPO catalytic materials. I will end by describing my current efforts on SAPO molecular sieves.

Figure 1

Figure 1. Left shows the atomic arrangement in SAPO-37, Right shows the topology of VPI-5.

References:

1.
Wilson, S.T., Lok, B.M., et al., “Aluminophosphate Molecular Sieves: A new Class of Microporous Crystalline Solids,” J. Am. Chem. Soc. 104, 1146-1147 (1982).
2.
Lok, B.M., Messina, C.A., et al., US Patent 4,440,871 (1984).
3.
L. Sierra de Saldarriaga, C. Saldarriaga, and M. E. Davis, "Investigations into the Nature of a Silicoaluminophosphate with the Faujasite Structure," J. Am. Chem. Soc. 109, 2686-2691 (1987).
4.
D. Hasha, L. Sierra de Saldarriaga, C. Saldarriaga, P. Hathaway, D. F. Cox, and M. E. Davis, "Studies of Silicoaluminophosphates with the Sodalite Structure," J. Am. Chem. Soc. 110, 2127-2135 (1988).
5.
M. E. Davis, C. Saldarriaga, C. Montes, J. Garces, and C. Crowder, "A Molecular Sieve with Eighteen-Membered Rings," Nature 331, 698-699 (1988).