Douglas M. Ruthven Professor   • B.A. University of Cambridge, 1960 • M.A. University of Cambridge, 1963 • Ph.D. University of Cambridge, 1966 • Sc.D. University of Cambridge, 1988   Phone: 207-581-2283 Fax: 207-581-2323 Email: druthven@umche.maine.edu

Research Interests

Fundamentals of adsorption • adsorption processes

Current Research

Micropore Diffusion

In small pores of molecular dimensions, the mechanism of transport of guest molecules is quite different from that which prevails in larger pores. Steric hindrance and electrostatic interactions become important and, as a result, under favorable circumstances, very large differences in diffusivity may be observed between similar molecules. This provides the basis for "molecular sieve" separations, which are increasingly exploited in the petroleum, petrochemical and associated industries. Present projects include detailed studies of diffusion of the xylene isomers in silicalite crystals and comparative studies of sorption kinetics in liquid phase and vapor phase adsorption systems.

Rapid Cycle Pressure Swing Adsorption (PSA) Processes

One way to increase the throughput of an adsorption separation process is to increase the feed rate and decrease proportionately the cycle time. However, the success of this approach is limited by the pressure drop/mass transfer characteristics of the adsorbent contactor which, for a traditional packed adsorbent bed, are not very favorable. A parallel passage contactor with sufficiently small spacing between the adsorbent layers shows a more favorable balance between pressure drop and mass transfer resistance. Novel methods of producing such contactors are being studied and their performances tested in a rapid cycle PSA rig.

Recovery of Methane from Low Grade Natural Gas

There are numerous deposits of low BTU natural gas containing nitrogen at concentration levels that preclude direct transfer to the pipeline system. Present processes for removal of nitrogen are not cost effective but adsorption appears to offer a promising alternative approach. The challenge is to find an adsorbent with a sufficiently high selectivity for nitrogen relative to methane.

Selected Publications

Books and Book Chapters

K. Knaebel, D.M. Ruthven, J.L. Humphrey and R. Carr, “Adsorption Technologies”, Chapter 2 in Emerging Separation and Separative Reaction Technologies for Process Waste Reduction, P. Radecki, J.C. Crittenden, D.R. Shonnard and J.L. Bulloch eds; pp 33-129 AIChE, New York (1999).

D.M. Ruthven and M.R.M. Post, “Diffusion in Zeolite Molecular Sieves”, Chapter 11 in Introduction to Zeolite Science and Practice, H. van Bekkum, E.M. Flanigen and J.C. Jansen eds. 2^nd ed. Elsevier, Amsterdam (1999).

Ruthven, D.M., S. Farooq and K. Knaebel, Pressure Swing Adsorption, 352 pp., VCH, NY (1994).

Kärger, J. and D.M. Ruthven, Diffusion in Zeolites and Other Microporous Solids, 604 pp., John Wiley, NY (1992).

D.M. Ruthven, Principles of Adsorption and Adsorption Processes, 433 pp., John Wiley, NY (1984).

Selected Papers

F. Brandani and D.M. Ruthven, “Measurement of Adsorption Equilibrium by the Zero Length Column (ZLC) Technique. Part 2: Binary Systems”, Ind. Eng. Chem. Res. 42, 1462-1469 (2003)

F. Brandani, D.M. Ruthven and C.G. Coe, “Measurement of Adsorption Equilibrium by the Zero Length Column (ZLC) Technique. Part 1: Single Component Systems”, Ind. Eng. Chem. Res. 42, 1451-1461 (2003)

D.S.C. Phelps and D.M. Ruthven, “Experimental and Theoretical Study of the Performance of a Continuous Counter-Current Adsorber”, Adsorption 9, 265-274 (2003)

H. MacDougall, D.M. Ruthven and S. Brandani, “Sorption and Diffusion of SF₆ in Silicalite Crystals”, Adsorption 5, 369-373 (1999).

S. Brandani, K. Austin and D.M. Ruthven, “Flow Pattern and Residence Time Distribution for an Endless-Belt-Solid-Liquid Contactor”, Chem. Eng. Sci. 54, 417-432 (1999).

S. Brandani, C. Cavalcante, A. Guimaraes and D.M. Ruthven, “Heat Effects in ZLC Experiments”, Adsorption, 4, 275-285 (1998).

S. Farooq, C. Thaeron and D.M. Ruthven, “Numerical Simulation of a Parallel Passage Piston Driven PSA Unit”, Separation and Purification Technology, 13, 181-193 (1998).

D.M. Ruthven and B.K. Kaul, “Compensation Theory of Adsorption:  Correlation and Prediction of Henry Constants for linear Paraffins in Zeolites”, Adsorption, 4, 269-273 (1998).

L. Boulicaut, S. Brandani and D.M. Ruthven, “Liquid Phase Sorption and Diffusion of Branched and Cyclic Hydrocarbons in Silacalite”, Microporous Materials, 25, 81-93 (1998).

S. Farooq, C. Thaeron and D.M. Ruthven, “Numerical Simulation of a Piston Driven PSA Unit”, Separation and Purification Technology, 13, 181-193 (1998).

D.M. Ruthven, “Characterization of Zeolites by Sorption Capacity Measurements”, Macroporous Materials, 22, 537-541 (1998).

C.L. Cavalcante, S. Brandani and D.M. Ruthven, “Evaluation of the Main Diffusion Path in Zeolites from ZLC Desorption Curves”, Zeolites, 18, 282-285 (1997).

S. Brandani, D.M. Ruthven and J. Kärger, “Diffusion in a Unidimensional Zeolite Pore System:  Propane in AlPO₄-5”, Microporous Materials, 8, 193-200 (1997).

M.A. Jama, M.P.F. Delmas and D.M. Ruthven, “Diffusion of Linear and Branched C₆ Hydrocarbons in Silicalite Studied by the Wall Coated Capillary Chromatographic Method”, Zeolites 18, 200-204 (1997).

Ruthven, D.M. and S. Sircar, "Design of Membrane and PSA Process for Bulk Gas Separation," Fourth International Conference on Foundation of Computer Aided Design, L.T. Biegler and M.F. Doherty, eds., AIChE Symp. Series 91(304), 29-37 (1995).

Delmas, M.P.F. and D.M. Ruthven, "Measurement of Intracrystalline Diffusion in NaX Zeolite by Capillary Column Chromatography," Microporous Materials, 3, 581-592 (1995).

Delmas, M.P.F., C. Cornu and D.M. Ruthven, "Measurement of Diffusion in Small 5A Zeolite Crystals by a Wall Coated Column Technique," Zeolites, 15, 45-50 (1995).

Cavalcante, C. and D.M. Ruthven, "Adsorption of Branched and Cyclic Paraffin in Silicalite II - Kinetics," I&EC Research, 34, 185-191 (1995).

Cavalcante, C. and D.M. Ruthven, "Adsorption of Branched and Cyclic Paraffin in Silicalite I - Equilibrium," I&EC Research, 34, 177-184 (1995).

Cavalcante, C.L., M. Eic, D.M. Ruthven and M. Occelli, "Diffusion of u-Paraffins in Offretite-Erionite Zeolites," Zeolites, 15, 293-307 (1995).

Brandani, S., D.M. Ruthven and J. Kärger, "Concentration Dependence of Self-Diffusivity of Methanol in NaX Zeolite Crystals," Zeolites, 15, 494-496 (1995).

Brandani S. and D.M. Ruthven, "Analysis of ZLC Desorption Curves for Liquid Systems," Chem. Eng. Sci., 50, 2055-2059 (1995).