A new combined-technique frequency response apparatus has been developed for studying mass transfer in porous adsorbents. This new apparatus can perform pressure-swing, volume-swing, and concentration-swing frequency response experiments, enabling it to investigate mass transfer of pure components and binary gas mixtures in adsorbents over a wide frequency range. To demonstrate the capabilities of the apparatus, pressure-swing and volume-swing frequency response experiments were performed in tandem to study transport of pure CO2 in 13X zeolite beads over the frequency range from 10(-4) Hz to 10 Hz at pressures from 0.125 to 1 bar. Frequency response spectra show that transport in this system is governed by a nonisothermal macropore diffusion resistance with diffusion occurring by a Knudsen-type mechanism. Macropore diffusion control is confirmed by the existence of particle size dependence of the system's dynamic response. In smaller zeolite particles, the macropore diffusion resistance is lower, and macropore diffusion becomes less important to the system response.