{"id":{"repo_id":"aachen","oai_identifier":"oai:publications.rwth-aachen.de:51337"},"canonical_url":"https://search.dev.ndltd.org/etd/aachen/oai:publications.rwth-aachen.de:51337","repository":{"repo_id":"aachen","name":"RWTH Aachen University","base_url":"https://publications.rwth-aachen.de/oai2d"},"display":{"title":"Untersuchungen an FeMoO-Katalysatoren zur Formaldehydproduktion","abstract":"The research aim of this work was the modification of the iron molybdate catalyst for the methanol oxidation to formaldehyde for the reduction of the active mass without losses of formaldehyde yield. Another main focus was the investigation of the surface species. Up to now iron molybdate catalysts for methanol oxidation are produced by pressing of the active mass into rings (bulk catalyst). The active mass content could be lowered by coating of support rings with the active mass from 100 to 20% (shell catalyst). The preparation of impregnated catalysts served for further reduction of the active mass for the methanol oxidation to formaldehyde to save raw materials. The impregnated catalysts are shell catalysts. Iron- and molybdenum-impregnated support material was used as active mass. The active mass of the catalysts with monolayer loading was only 1.4 Gew% according to the total weight of the catalyst. It could be produced comparably, good catalysts in spite of 98.6% reduction of the active mass. For the improvement of the catalyst performance different Mo:Fe atomic ratios and loadings were prepared and tested. Because impregnating is very costly by incipient wetness method in the large-scale technical graduation, another, spreaded catalyst with double monolayer loading was prepared after a new developed hybrid synthesis method. The iron and molybdenum component are applied by electrostatic attraction on the support material in aqueous dissolution. The formaldehyde yield per active mass of the incipient wetness impregnated catalyst and the hybrid synthesis impregnated catalyst is very similar and approx. 10 times higher in comparison to the bulk and shell catalyst. The catalyst performance of the impregnated catalysts could be increased by the change of the Mo:Fe atomic ratio and the loading in comparison to the shell and bulk catalyst. This improvement can be due to the activity increase and reduction of the active mass content without formaldehyde selectivity losses of the impregnated catalysts. The formaldehyde selectivity could not be increased by the change of the composition of the active mass in comparison to the bulk and shell catalyst. Nevertheless, this could be reached by the optimisation of the Mo:Fe atomic ratio, the impregnation and the support material. All catalysts with double monolayer loading show in the Raman spectrum a signal which can be assigned to a octahedral, polymeric surface molybdenum species. These molybdenum species could be the formaldehyde-selective site. By XPS and ISS results is evident that the surface of the bulk and shell catalyst is molybdenum enriched. The molybdenum enrichment is coined differently. Molybdenum seems to be the formaldehyde-selective site. This site and with it the activity and formaldehyde selectivity of the catalyst is changed by different surroundings. As with the bulk and shell catalyst the surface of the impregnated catalyst is molybdenum enriched. Accordingly the iron component should be inside of pores and the active MoFe species on the external surface. This assumption is supported by the ISS results. Because of this information the active mass could be possibly imagine in such a way that an iron atom is directly on the support surface and the octamolybdate species spans this iron atom like a hemisphere. This is in harmony with the increasing Mo:Fe atomic ratio on the support surface according to ISS and the Raman signal close to octamolybdates. Therefore, the iron component is necessary as promoter. Beside iron other promoters could have a positive effect for the methanol oxidation to formaldehyde. The infrared measurements have shown that a large part of the acid hydroxyl groups of the support surface react by impregnation possibly after the following reaction –A-OH + HO-Mo- to -A-O-Mo- + H2O So, they are not available any more for formation of dimethyl ether. This assumption is supported by the low dimethyl ether selectivity of the impregnated catalysts","abstract_html":"The research aim of this work was the modification of the iron molybdate catalyst for the methanol oxidation to formaldehyde for the reduction of the active mass without losses of formaldehyde yield. Another main focus was the investigation of the surface species. Up to now iron molybdate catalysts for methanol oxidation are produced by pressing of the active mass into rings (bulk catalyst). The active mass content could be lowered by coating of support rings with the active mass from 100 to 20% (shell catalyst). The preparation of impregnated catalysts served for further reduction of the active mass for the methanol oxidation to formaldehyde to save raw materials. The impregnated catalysts are shell catalysts. Iron- and molybdenum-impregnated support material was used as active mass. The active mass of the catalysts with monolayer loading was only 1.4 Gew% according to the total weight of the catalyst. It could be produced comparably, good catalysts in spite of 98.6% reduction of the active mass. For the improvement of the catalyst performance different Mo:Fe atomic ratios and loadings were prepared and tested. Because impregnating is very costly by incipient wetness method in the large-scale technical graduation, another, spreaded catalyst with double monolayer loading was prepared after a new developed hybrid synthesis method. The iron and molybdenum component are applied by electrostatic attraction on the support material in aqueous dissolution. The formaldehyde yield per active mass of the incipient wetness impregnated catalyst and the hybrid synthesis impregnated catalyst is very similar and approx. 10 times higher in comparison to the bulk and shell catalyst. The catalyst performance of the impregnated catalysts could be increased by the change of the Mo:Fe atomic ratio and the loading in comparison to the shell and bulk catalyst. This improvement can be due to the activity increase and reduction of the active mass content without formaldehyde selectivity losses of the impregnated catalysts. The formaldehyde selectivity could not be increased by the change of the composition of the active mass in comparison to the bulk and shell catalyst. Nevertheless, this could be reached by the optimisation of the Mo:Fe atomic ratio, the impregnation and the support material. All catalysts with double monolayer loading show in the Raman spectrum a signal which can be assigned to a octahedral, polymeric surface molybdenum species. These molybdenum species could be the formaldehyde-selective site. By XPS and ISS results is evident that the surface of the bulk and shell catalyst is molybdenum enriched. The molybdenum enrichment is coined differently. Molybdenum seems to be the formaldehyde-selective site. This site and with it the activity and formaldehyde selectivity of the catalyst is changed by different surroundings. As with the bulk and shell catalyst the surface of the impregnated catalyst is molybdenum enriched. Accordingly the iron component should be inside of pores and the active MoFe species on the external surface. This assumption is supported by the ISS results. Because of this information the active mass could be possibly imagine in such a way that an iron atom is directly on the support surface and the octamolybdate species spans this iron atom like a hemisphere. This is in harmony with the increasing Mo:Fe atomic ratio on the support surface according to ISS and the Raman signal close to octamolybdates. Therefore, the iron component is necessary as promoter. Beside iron other promoters could have a positive effect for the methanol oxidation to formaldehyde. The infrared measurements have shown that a large part of the acid hydroxyl groups of the support surface react by impregnation possibly after the following reaction –A-OH + HO-Mo- to -A-O-Mo- + H2O So, they are not available any more for formation of dimethyl ether. This assumption is supported by the low dimethyl ether selectivity of the impregnated catalysts","abstract_has_math":false,"creators":["Walzel, Inga"],"institution":"Publikationsserver der RWTH Aachen University","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Liauw, Marcel"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2009,"date_issued":"2009","date_published":"2009","updated_at":"2026-07-30T19:40:33Z","subjects":["info:eu-repo/classification/ddc/540","Formaldehyd","Chemie","formaldehyde"],"languages":["ger"],"rights":["info:eu-repo/semantics/openAccess"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-113639%22"],"render_values":[{"text":"https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-113639%22","href":"https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-113639%22","code":true}]}]},"links":{"outbound_url":"https://publications.rwth-aachen.de/record/51337","outbound_label":"Repository record","outbound_source":"dc:identifier"},"source_record":{"url":"https://publications.rwth-aachen.de/oai2d?verb=GetRecord&metadataPrefix=oai_dc&identifier=oai%3Apublications.rwth-aachen.de%3A51337","prefix":"oai_dc"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Liauw, Marcel"]},{"key":"dc:creator","label":"Author","values":["Walzel, Inga"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:coverage","label":"Dc Coverage","values":["DE"]},{"key":"dc:date","label":"Dc Date","values":["2009"]},{"key":"dc:publisher","label":"Institution","values":["Publikationsserver der RWTH Aachen University"]},{"key":"dc:relation","label":"Dc Relation","values":["info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:hbz:82-opus-31129"]},{"key":"dc:type","label":"Dc Type","values":["info:eu-repo/semantics/doctoralThesis","info:eu-repo/semantics/publishedVersion"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["info:eu-repo/classification/ddc/540","Formaldehyd","Chemie","formaldehyde"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["ger"]},{"key":"dc:rights","label":"Dc Rights","values":["info:eu-repo/semantics/openAccess"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://publications.rwth-aachen.de/record/51337","https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-113639%22"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The research aim of this work was the modification of the iron molybdate catalyst for the methanol oxidation to formaldehyde for the reduction of the active mass without losses of formaldehyde yield. Another main focus was the investigation of the surface species. Up to now iron molybdate catalysts for methanol oxidation are produced by pressing of the active mass into rings (bulk catalyst). The active mass content could be lowered by coating of support rings with the active mass from 100 to 20% (shell catalyst). The preparation of impregnated catalysts served for further reduction of the active mass for the methanol oxidation to formaldehyde to save raw materials. The impregnated catalysts are shell catalysts. Iron- and molybdenum-impregnated support material was used as active mass. The active mass of the catalysts with monolayer loading was only 1.4 Gew% according to the total weight of the catalyst. It could be produced comparably, good catalysts in spite of 98.6% reduction of the active mass. For the improvement of the catalyst performance different Mo:Fe atomic ratios and loadings were prepared and tested. Because impregnating is very costly by incipient wetness method in the large-scale technical graduation, another, spreaded catalyst with double monolayer loading was prepared after a new developed hybrid synthesis method. The iron and molybdenum component are applied by electrostatic attraction on the support material in aqueous dissolution. The formaldehyde yield per active mass of the incipient wetness impregnated catalyst and the hybrid synthesis impregnated catalyst is very similar and approx. 10 times higher in comparison to the bulk and shell catalyst. The catalyst performance of the impregnated catalysts could be increased by the change of the Mo:Fe atomic ratio and the loading in comparison to the shell and bulk catalyst. This improvement can be due to the activity increase and reduction of the active mass content without formaldehyde selectivity losses of the impregnated catalysts. The formaldehyde selectivity could not be increased by the change of the composition of the active mass in comparison to the bulk and shell catalyst. Nevertheless, this could be reached by the optimisation of the Mo:Fe atomic ratio, the impregnation and the support material. All catalysts with double monolayer loading show in the Raman spectrum a signal which can be assigned to a octahedral, polymeric surface molybdenum species. These molybdenum species could be the formaldehyde-selective site. By XPS and ISS results is evident that the surface of the bulk and shell catalyst is molybdenum enriched. The molybdenum enrichment is coined differently. Molybdenum seems to be the formaldehyde-selective site. This site and with it the activity and formaldehyde selectivity of the catalyst is changed by different surroundings. As with the bulk and shell catalyst the surface of the impregnated catalyst is molybdenum enriched. Accordingly the iron component should be inside of pores and the active MoFe species on the external surface. This assumption is supported by the ISS results. Because of this information the active mass could be possibly imagine in such a way that an iron atom is directly on the support surface and the octamolybdate species spans this iron atom like a hemisphere. This is in harmony with the increasing Mo:Fe atomic ratio on the support surface according to ISS and the Raman signal close to octamolybdates. Therefore, the iron component is necessary as promoter. Beside iron other promoters could have a positive effect for the methanol oxidation to formaldehyde. The infrared measurements have shown that a large part of the acid hydroxyl groups of the support surface react by impregnation possibly after the following reaction –A-OH + HO-Mo- to -A-O-Mo- + H2O So, they are not available any more for formation of dimethyl ether. This assumption is supported by the low dimethyl ether selectivity of the impregnated catalysts"]},{"key":"dc:source","label":"Dc Source","values":["Aachen : Publikationsserver der RWTH Aachen University 130 S. : graph. Darst. (2009). = Aachen, Techn. Hochsch., Diss., 2009"]},{"key":"dc:title","label":"Title","values":["Untersuchungen an FeMoO-Katalysatoren zur Formaldehydproduktion"]}]}],"canonical_facts":{"dc:contributor":["Liauw, Marcel"],"dc:coverage":["DE"],"dc:creator":["Walzel, Inga"],"dc:date":["2009"],"dc:description":["The research aim of this work was the modification of the iron molybdate catalyst for the methanol oxidation to formaldehyde for the reduction of the active mass without losses of formaldehyde yield. Another main focus was the investigation of the surface species. Up to now iron molybdate catalysts for methanol oxidation are produced by pressing of the active mass into rings (bulk catalyst). The active mass content could be lowered by coating of support rings with the active mass from 100 to 20% (shell catalyst). The preparation of impregnated catalysts served for further reduction of the active mass for the methanol oxidation to formaldehyde to save raw materials. The impregnated catalysts are shell catalysts. Iron- and molybdenum-impregnated support material was used as active mass. The active mass of the catalysts with monolayer loading was only 1.4 Gew% according to the total weight of the catalyst. It could be produced comparably, good catalysts in spite of 98.6% reduction of the active mass. For the improvement of the catalyst performance different Mo:Fe atomic ratios and loadings were prepared and tested. Because impregnating is very costly by incipient wetness method in the large-scale technical graduation, another, spreaded catalyst with double monolayer loading was prepared after a new developed hybrid synthesis method. The iron and molybdenum component are applied by electrostatic attraction on the support material in aqueous dissolution. The formaldehyde yield per active mass of the incipient wetness impregnated catalyst and the hybrid synthesis impregnated catalyst is very similar and approx. 10 times higher in comparison to the bulk and shell catalyst. The catalyst performance of the impregnated catalysts could be increased by the change of the Mo:Fe atomic ratio and the loading in comparison to the shell and bulk catalyst. This improvement can be due to the activity increase and reduction of the active mass content without formaldehyde selectivity losses of the impregnated catalysts. The formaldehyde selectivity could not be increased by the change of the composition of the active mass in comparison to the bulk and shell catalyst. Nevertheless, this could be reached by the optimisation of the Mo:Fe atomic ratio, the impregnation and the support material. All catalysts with double monolayer loading show in the Raman spectrum a signal which can be assigned to a octahedral, polymeric surface molybdenum species. These molybdenum species could be the formaldehyde-selective site. By XPS and ISS results is evident that the surface of the bulk and shell catalyst is molybdenum enriched. The molybdenum enrichment is coined differently. Molybdenum seems to be the formaldehyde-selective site. This site and with it the activity and formaldehyde selectivity of the catalyst is changed by different surroundings. As with the bulk and shell catalyst the surface of the impregnated catalyst is molybdenum enriched. Accordingly the iron component should be inside of pores and the active MoFe species on the external surface. This assumption is supported by the ISS results. Because of this information the active mass could be possibly imagine in such a way that an iron atom is directly on the support surface and the octamolybdate species spans this iron atom like a hemisphere. This is in harmony with the increasing Mo:Fe atomic ratio on the support surface according to ISS and the Raman signal close to octamolybdates. Therefore, the iron component is necessary as promoter. Beside iron other promoters could have a positive effect for the methanol oxidation to formaldehyde. The infrared measurements have shown that a large part of the acid hydroxyl groups of the support surface react by impregnation possibly after the following reaction –A-OH + HO-Mo- to -A-O-Mo- + H2O So, they are not available any more for formation of dimethyl ether. This assumption is supported by the low dimethyl ether selectivity of the impregnated catalysts"],"dc:identifier":["https://publications.rwth-aachen.de/record/51337","https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-113639%22"],"dc:language":["ger"],"dc:publisher":["Publikationsserver der RWTH Aachen University"],"dc:relation":["info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:hbz:82-opus-31129"],"dc:rights":["info:eu-repo/semantics/openAccess"],"dc:source":["Aachen : Publikationsserver der RWTH Aachen University 130 S. : graph. Darst. (2009). = Aachen, Techn. Hochsch., Diss., 2009"],"dc:subject":["info:eu-repo/classification/ddc/540","Formaldehyd","Chemie","formaldehyde"],"dc:title":["Untersuchungen an FeMoO-Katalysatoren zur Formaldehydproduktion"],"dc:type":["info:eu-repo/semantics/doctoralThesis","info:eu-repo/semantics/publishedVersion"]},"updated_at":"2026-07-30T19:40:33Z"}