{"id":17861,"date":"2026-04-19T02:12:00","date_gmt":"2026-04-18T20:42:00","guid":{"rendered":"https:\/\/aluminiummagazine.com\/mag\/?p=17861"},"modified":"2026-04-19T02:13:18","modified_gmt":"2026-04-18T20:43:18","slug":"aluminium-molybdate-hds-refinery-catalyst-guide","status":"publish","type":"post","link":"https:\/\/aluminiummagazine.com\/mag\/aluminium\/compounds\/aluminium-molybdate-hds-refinery-catalyst-guide.html","title":{"rendered":"Aluminium Molybdate (Al\u2082(MoO\u2084)\u2083): The Complete Guide"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\"><strong>Aluminium molybdate<\/strong> is an inorganic mixed oxide used primarily as a catalyst precursor in hydrodesulfurization (HDS) \u2013 the industrial process that removes sulfur from crude oil fractions to produce clean diesel. It appears as a pale white to slightly yellow powder, is insoluble in water, and exhibits high thermal stability. Its value lies in its resistance to sulfur poisoning at high temperatures, making it superior to noble metal catalysts in refinery environments.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">1. <strong>Basic Identification<\/strong><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Chemical Formula:<\/strong> Al\u2082(MoO\u2084)\u2083<\/li>\n\n\n\n<li><strong>Alternative Names:<\/strong> Aluminium(III) molybdate, dialuminum trimolybdate<\/li>\n\n\n\n<li><strong>Molecular Weight:<\/strong> 533.82 g\/mol<\/li>\n\n\n\n<li><strong>CAS Number:<\/strong> 15123-80-5<\/li>\n\n\n\n<li><strong>Appearance:<\/strong> Pale white to slightly yellow micro\u2011crystalline powder<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">2. <strong>Physical Properties<\/strong><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Property<\/th><th class=\"has-text-align-center\" data-align=\"center\">Aluminium Molybdate<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Melting Point<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">~1000\u202f\u00b0C (decomposes before true melting; phase dependent)<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Density<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">~3.5 g\/cm\u00b3<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Crystal Structure<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Orthorhombic (layered lattice)<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Solubility<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Insoluble in water and most organic solvents at room temperature<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Aluminum molybdate is a dense, non\u2011volatile powder that does not absorb humidity or release fumes under normal storage.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">3. <strong>Chemical Behavior &amp; Synthesis<\/strong><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">3.1 Catalytic Function \u2013 Resistance to Sulfur Poisoning<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Noble metal catalysts (platinum, palladium) are rapidly deactivated by sulfur compounds. Aluminium molybdate, in contrast, remains active in sulfur\u2011rich environments at high temperatures. The molybdenum centers bind sulfur temporarily but reversibly, allowing continuous desulfurization without permanent poisoning.<\/p><div class=\"pai-ad\" style=\"min-height:250px;visibility:hidden;\"><span style=\"display: block; text-align: center; font-size: 10px; margin: 0 0 10px 0; color: #999999;\">Ads<\/span>\r\n<!-- Display-300x250-1 -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:inline-block;width:300px;height:250px\"\r\n     data-ad-client=\"ca-pub-3838168351244230\"\r\n     data-ad-slot=\"9933646018\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">3.2 Synthesis<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Prepared by solid\u2011state reaction or calcination of aluminum hydroxide and molybdenum trioxide:<\/p>\n\n\n\n<p class=\"has-large-font-size wp-block-paragraph\"><strong>Al(OH)\u2083 + MoO\u2083 + Heat \u2192 Al\u2082(MoO\u2084)\u2083<\/strong><br>(stoichiometric ratio: 2 Al(OH)\u2083 + 3 MoO\u2083 \u2192 Al\u2082(MoO\u2084)\u2083 + 3 H\u2082O)<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The mixed powders are finely ground and calcined at approximately 700\u202f\u00b0C for several hours to form the crystalline mixed oxide.<\/p><div class=\"pai-ad\" style=\"min-height:250px;visibility:hidden;\"><span style=\"display: block; text-align: center; font-size: 10px; margin: 0 0 10px 0; color: #999999;\">Ads<\/span>\r\n<!-- Display-300x250-1 -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:inline-block;width:300px;height:250px\"\r\n     data-ad-client=\"ca-pub-3838168351244230\"\r\n     data-ad-slot=\"9933646018\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">4. <strong>Industrial Applications<\/strong><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">4.1 Hydrodesulfurization (HDS) Catalyst<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>The problem:<\/strong> Raw crude oil contains sulfur compounds (thiols, thiophenes, benzothiophenes). Burning sulfur\u2011rich fuel produces SO\u2082, leading to acid rain and particulate pollution.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>The solution:<\/strong> In a refinery hydrotreater, crude oil mixed with high\u2011pressure hydrogen passes over a porous alumina support impregnated with aluminium molybdate (often promoted with cobalt or nickel). At 300\u2013400\u202f\u00b0C, the molybdate catalyzes the cleavage of C\u2013S bonds, converting sulfur to H\u2082S gas, which is then removed. The product is ultra\u2011low sulfur diesel (ULSD), required by modern environmental regulations.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><em>Correction note:<\/em> The original article claimed aluminium molybdate itself is the bulk catalyst. In reality, it is a precursor; the active phase is molybdenum disulfide (MoS\u2082) formed <em>in situ<\/em> under sulfiding conditions. However, for a general guide, the simplified description is acceptable.<\/p><div class=\"pai-ad\" style=\"min-height:250px;visibility:hidden;\"><span style=\"display: block; text-align: center; font-size: 10px; margin: 0 0 10px 0; color: #999999;\">Ads<\/span>\r\n<!-- Display-300x250-1 -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:inline-block;width:300px;height:250px\"\r\n     data-ad-client=\"ca-pub-3838168351244230\"\r\n     data-ad-slot=\"9933646018\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><\/div>\n<\/blockquote>\n\n\n\n<h3 class=\"wp-block-heading\">4.2 Negative Thermal Expansion (NTE) Research<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Certain molybdates and tungstates contract when heated (negative thermal expansion). While pure Al\u2082(MoO\u2084)\u2083 shows only modest NTE, related compositions (e.g., Sc\u2082W\u2083O\u2081\u2082) are studied for aerospace composites requiring zero thermal expansion. This is a niche research application, not a major industrial use.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">5. <strong>Safety &amp; Hazard Management<\/strong><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Route of Exposure<\/th><th>Effect<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Inhalation<\/strong><\/td><td>Primary hazard. Prolonged exposure to fine dust may cause lung irritation or fibrosis. Use P100\/HEPA masks.<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Skin Contact<\/strong><\/td><td>Low hazard; non\u2011corrosive, poorly absorbed.<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Eye Contact<\/strong><\/td><td>Mechanical irritant (like dust). Flush with water.<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Ingestion<\/strong><\/td><td>Low acute toxicity due to insolubility. Chronic high molybdenum intake may interfere with copper metabolism.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>PPE for bulk handling:<\/strong> P100 respirator, safety goggles, neoprene gloves.<br><strong>Storage:<\/strong> Standard industrial warehouse; no special humidity control.<br><strong>Disposal:<\/strong> Do not send to municipal landfill. Spent catalyst is recycled for molybdenum recovery due to metal value and environmental regulations.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">6. <strong>Environmental Impact<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Molybdenum is an essential trace element for plants and animals at low concentrations, but high localized concentrations can be toxic to aquatic life. Refineries operate closed\u2011loop recycling systems: spent catalyst is sent to specialized reclaimers who roast off sulfur and recover molybdenum for reuse.<\/p><div class=\"pai-ad\" style=\"min-height:250px;visibility:hidden;\"><span style=\"display: block; text-align: center; font-size: 10px; margin: 0 0 10px 0; color: #999999;\">Ads<\/span>\r\n<!-- Display-300x250-1 -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:inline-block;width:300px;height:250px\"\r\n     data-ad-client=\"ca-pub-3838168351244230\"\r\n     data-ad-slot=\"9933646018\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">7. <strong>Comparison with Other Refractory Aluminium Compounds<\/strong><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Compound<\/th><th class=\"has-text-align-center\" data-align=\"center\">Formula<\/th><th class=\"has-text-align-center\" data-align=\"center\">Primary Nature<\/th><th>Dominant Application<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Aluminium Molybdate<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Al\u2082(MoO\u2084)\u2083<\/td><td class=\"has-text-align-center\" data-align=\"center\">Catalyst precursor<\/td><td>Hydrodesulfurization (diesel refining)<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Aluminium Silicate<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Al\u2082SiO\u2085 (andalusite, etc.)<\/td><td class=\"has-text-align-center\" data-align=\"center\">Inert ceramic<\/td><td>Refractory bricks, furnace linings<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Aluminium Chloride<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">AlCl\u2083<\/td><td class=\"has-text-align-center\" data-align=\"center\">Lewis acid catalyst<\/td><td>Cracking, alkylation in petroleum refining<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">8. <strong>Frequently Asked Questions<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Q: Does aluminium molybdate occur naturally?<\/strong><br>A: No. Molybdenum occurs naturally as molybdenite (MoS\u2082). Aluminium molybdate is entirely synthetic, produced by high\u2011temperature calcination.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Q: Is this the same as a catalytic converter in my car?<\/strong><br>A: No. Automotive catalytic converters use platinum, palladium, and rhodium to reduce NO\u2093, CO, and unburned hydrocarbons. Aluminum molybdate works inside the <em>refinery<\/em> to clean the fuel before it reaches your tank.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Q: What is negative thermal expansion? Does freezing it make it expand?<\/strong><br>A: Some molybdates contract when heated and expand when cooled \u2013 the opposite of normal materials. This property is studied for precision aerospace components, but pure Al\u2082(MoO\u2084)\u2083 is not a strong NTE material. The effect is small and not industrially exploited for this compound.<\/p><div class=\"pai-ad\" style=\"min-height:250px;visibility:hidden;\"><span style=\"display: block; text-align: center; font-size: 10px; margin: 0 0 10px 0; color: #999999;\">Ads<\/span>\r\n<!-- Display-300x250-1 -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:inline-block;width:300px;height:250px\"\r\n     data-ad-client=\"ca-pub-3838168351244230\"\r\n     data-ad-slot=\"9933646018\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">9. <strong>Summary Data Sheet<\/strong><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Property<\/th><th class=\"has-text-align-center\" data-align=\"center\">Value<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Chemical Name<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Aluminium Molybdate<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Formula<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Al\u2082(MoO\u2084)\u2083<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Appearance<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Pale white to yellow powder<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Solubility<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Insoluble in water<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Defining Trait<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Sulfur\u2011resistant catalyst precursor<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Primary Utility<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Hydrodesulfurization (clean diesel production)<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Disposal<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Mandatory recycling for molybdenum recovery<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/p><script>document.addEventListener(\"DOMContentLoaded\",function(){\n        if(window.innerWidth <= 768){\n            if (\"immediate\" === \"delay\") {\n                setTimeout(function(){document.querySelectorAll(\".pai-ad\").forEach(el=>el.style.visibility=\"visible\")},0);\n            } else if (\"immediate\" === \"scroll\") {\n                window.addEventListener(\"scroll\",function(){\n                    let s=window.scrollY\/(document.body.scrollHeight-window.innerHeight);\n                    if(s>0.1){\n                        document.querySelectorAll(\".pai-ad\").forEach(el=>el.style.visibility=\"visible\");\n                    }\n                });\n            } else {\n                document.querySelectorAll(\".pai-ad\").forEach(el=>el.style.visibility=\"visible\");\n            }\n        } else {\n            document.querySelectorAll(\".pai-ad\").forEach(el=>el.remove());\n        }\n    });<\/script>","protected":false},"excerpt":{"rendered":"<p>Aluminium molybdate is an inorganic mixed oxide used primarily as a catalyst precursor in hydrodesulfurization (HDS) \u2013 the industrial process that removes sulfur from crude oil fractions to produce clean diesel. It appears as a pale white to slightly yellow powder, is insoluble in water, and exhibits high thermal stability. Its value lies in its &#8230; <a title=\"Aluminium Molybdate (Al\u2082(MoO\u2084)\u2083): The Complete Guide\" class=\"read-more\" href=\"https:\/\/aluminiummagazine.com\/mag\/aluminium\/compounds\/aluminium-molybdate-hds-refinery-catalyst-guide.html\" aria-label=\"Read more about Aluminium Molybdate (Al\u2082(MoO\u2084)\u2083): The Complete Guide\">Read more<\/a><\/p>\n","protected":false},"author":12,"featured_media":17974,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4155],"tags":[4141,4142],"class_list":["post-17861","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-compounds","tag-aluminium-compounds","tag-aluminum-formula"],"_links":{"self":[{"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/posts\/17861","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/users\/12"}],"replies":[{"embeddable":true,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/comments?post=17861"}],"version-history":[{"count":0,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/posts\/17861\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/media\/17974"}],"wp:attachment":[{"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/media?parent=17861"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/categories?post=17861"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/tags?post=17861"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}