Systematic kinetic studies on mixed gas hydrates by Raman spectroscopy and powder X-ray diffraction

► We present results from hydrate formation experiments regarding the guest geometry. ► The experiments were performed with a new pressure cell employing X-ray diffraction. ► At the enclathration-controlled stage the guest molecule size is not important. ► At the diffusion-controlled stage the guest molecule size is relevant. ► Formation of coexisting structure I and structure H hydrate crystals was observed.