A method for producing a three-dimensional porous transition alumina catalyst monolith of stacked catalyst fibers, comprising the following steps: a) Preparing a suspension paste in a liquid diluent of hydroxide precursor particles or oxyhydroxide precursor particles of transition alumina particles or mixtures thereof and which suspension can furthermore comprise a binder material in a maximum amount of 20 wt%, based on the amount of hydroxide precursor particles or oxyhydroxide precursor particles of transition alumina particles or mixtures thereof, wherein the binder material is selected from organic materials and/or a plasticizer chosen form organic materials in a maximum amount of 10 wt%, based on the amount of hydroxide precursor particles or oxyhydroxide precursor particles of transition alumina particles or mixtures thereof, all particles in the suspension having a number average particle size in the range of from 0.05 to 700 μm, b) extruding the paste of step a) through one or more nozzles to form fibers, and depositing the extruded fibers to form a three-dimensional porous catalyst monolith precursor, c) drying the porous catalyst monolith precursor to remove the liquid diluent, d) performing a temperature treatment of the dried porous catalyst monolith precursor of step c) at a temperature in the range of from 500 to 1000 °C, to form the transition alumina catalyst monolith, wherein no temperature treatment of the porous catalyst monolith precursor or porous catalyst monolith at temperatures above 1000 °C is performed and wherein no further catalytically active metals, metal oxides or metal compounds are applied to the surface of the transition alumina precursor particles, the catalyst monolith precursor or transition alumina catalyst monolith, wherein no dopants are added to the suspension paste and wherein the amount of impurities, selected from Li 2 O, Na 2 O, K 2 O, CaO, MgO, BaO, B 2 O 3 Ga 2 O 3, SiO 2, TiO 2, ZrO 2, ZnO, Fe 2 O 3. as well as chlorides, nitrates and sulfates in the final transition alumina, is not higher than 2.5 wt%, based on the transition alumina in the monolith or based on the amount of hydroxide precursor particles or oxyhydroxide precursor particles of transition alumina particles or mixtures thereof, wherein the average particle sizes are measured by sieving the particles or by laser diffraction techniques or by photographic techniques like camsizer techniques. a) Preparing a suspension paste in a liquid diluent of hydroxide precursor particles or oxyhydroxide precursor particles of transition alumina particles or mixtures thereof and which suspension can furthermore comprise a binder material in a maximum amount of 20 wt%, based on the amount of hydroxide precursor particles or oxyhydroxide precursor particles of transition alumina particles or mixtures thereof, wherein the binder material is selected from organic materials and/or a plasticizer chosen form organic materials in a maximum amount of 10 wt%, based on the amount of hydroxide precursor particles or oxyhydroxide precursor particles of transition alumina particles or mixtures thereof, all particles in the suspension having a number average particle size in the range of from 0.05 to 700 μm, b) extruding the paste of step a) through one or more nozzles to form fibers, and depositing the extruded fibers to form a three-dimensional porous catalyst monolith precursor, c) drying the porous catalyst monolith precursor to remove the liquid diluent, d) performing a temperature treatment of the dried porous catalyst monolith precursor of step c) at a temperature in the range of from 500 to 1000 °C, to form the transition alumina catalyst monolith, wherein no temperature treatment of the porous catalyst monolith precursor or porous catalyst monolith at temperatures above 1000 °C is performed and wherein no further catalytically active metals, metal oxides or metal compounds are applied to the surface of the transition alumina precursor particles, the catalyst monolith precursor or transition alumina catalyst monolith, wherein no dopants are added to the suspension paste and wherein the amount of impurities, selected from Li 2 O, Na 2 O, K 2 O, CaO, MgO, BaO, B 2 O 3 Ga 2 O 3, SiO 2, TiO 2, ZrO 2, ZnO, Fe 2 O 3. as well as chlorides, nitrates and sulfates in the final transition alumina, is not higher than 2.5 wt%, based on the transition alumina in the monolith or based on the amount of hydroxide precursor particles or oxyhydroxide precursor particles of transition alumina particles or mixtures thereof, wherein the average particle sizes are measured by sieving the particles or by laser diffraction techniques or by photographic techniques like camsizer techniques.