The author`s contribution Several people contributed to the Papers and manuscripts in this thesis. A description of Wegard Skistad`s contribution to each work is presented below. Paper I: Wegard Skistad has synthesized EU-1 and ZSM-48 catalysts, contributed to the characterization of the catalysts, interpretation of the results, and preparation of the manuscript. Paper II: Wegard Skistad has synthesized the catalysts and performed low pressure catalytic tests. He has contributed to the characterization of the catalysts, planning of the experiments, interpretation of the results, and preparation of the manuscript. Paper III: Wegard Skistad has synthesized TNU-9 and IM-5 catalysts, contributed to the characterization of the catalysts, interpretation of the results, and preparation of the manuscript. Paper IV: Wegard Skistad has synthesized TNU-9 and IM-5 and characterized the materials. He built a methanol pulse dosing system and performed the Raman spectroscopic investigation together with Francesca Bonino (University of Turin). He has contributed to the planning of the experiments, interpretation of the results, and preparation of the manuscript.

Four 3D 10-ring zeolites, IM-5, TNU-9, ZSM-11 and ZSM-5, with Si/Al = 14-24 and crystal sizes below 2 microns, were tested as catalysts for the methanol to hydrocarbons reaction (MTH) at atmospheric pressure, 350 °C and WHSV = 9 h(-1). All catalysts gave initially full methanol conversion, and showed strikingly similar effluent product selectivities. However, their life-time duration differed significantly, and decreased in the order: ZSM-11 > ZSM-5 ≫ TNU-9 > IM-5. A main difference between the two groups of stability behaviour was the size of cavities formed by channel intersections; larger cavities in TNU-9 and IM-5 leading to polyaromatics formation and a more rapid deactivation compared to ZSM-5 and ZSM-11. Effluent yield-conversion plots suggested that polymethylated benzene intermediates were more important in IM-5 and TNU-9 than in ZSM-5 and ZSM-11, where alkene methylation and cracking reactions seemed to dominate product formation. However, this difference had only minor influence on effluent selectivity.

a b s t r a c tZeolites are crystalline aluminosilicates that are widely used as shape-selective catalysts in the refinery and petrochemical industries. By synthesizing a series of structurally related zeolite catalyst and applying them in the industrially relevant conversion of methanol to hydrocarbons, new and extended understanding of the concept of shape selectivity has been reached. We have analyzed the relationship between particle morphology and pore system for catalysts having both small-and medium-sized pores using microscopy and diffraction, as well as performing extensive standard characterization. Two instances of preferential exposure of certain crystal facets, favoring access to one pore system over the other, have been found. Zeolites ZSM-57 (MFS) and SUZ-4 (SZR) both have both 8-and 10-ring channels. MFS prefers a plate-like or nanosheet-type morphology, where the 10-ring channels are perpendicular to the plates/sheets. This leads to favorable diffusion properties and a pronounced deactivation resistance. For SZR, needle-like crystals with high aspect ratio are preferred. In this instance, the sides of the needles are covered by the 8-ring pore openings, whereas the 10-ring pore openings are only exposed at the ends of the needles. This leads to unexpected product selectivity, as the material behaves essentially as an 8-ring catalyst. We argue that it should be possible to tune the shape selectivity of zeolite catalysts having pore systems of different dimensions by controlling the crystal morphology.

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Zeolites are widely used in the chemical industry for their catalytic properties and their ability to control the size and shape of both reactant and product molecules. In this presentation we will show unexpected catalytic properties of ZSM-57 and SUZ-4 during conversion of methanol to hydrocarbons (MTH). We have previously shown how analysis of anisotropic peak broadening in XRPD data [1] can reveal not only the average shape of the crystallites, but also how the zeolite channels are orientated relative to the morphology [2]. The same method was used to analyze the ZSM-57 and SUZ-4 samples revealing nano-sheet and -needle morphologies respectively. Electron imaging and diffraction furthermore revealed that the sheets of ZSM-57 are five-fold twinned with the 10-ring channel system perpendicular to the sheet. The 8-ring channel system would form a closed pentagon shape in defect free crystals. Based on these observations we will explain the remarkable MTH lifetime and selectivity displayed by the ZSM-57 and SUZ-4 samples respectively [3].[1] A. Katerinopoulou, T.