The CAS registry number 1317-33-5 for molybdenum disulfide is the core identifier for this substance within the global chemical regulatory framework. Assigned by the Chemical Abstracts Service, the CAS number is unique and permanent, serving as the basis for classification, registration, and traceability by customs authorities, inspection agencies, and end users worldwide. For MoS₂ manufacturers, traders, and end users, accurately understanding the compliance implications of CAS number 1317-33-5 under frameworks such as REACH, TSCA, and GHS is essential for ensuring smooth market access.

Basic Information for CAS Number 1317-33-5

CAS number 1317-33-5 corresponds to the chemical substance "Molybdenum Disulfide" with the molecular formula MoS₂ and molecular weight 160.07. In the ECHA (European Chemicals Agency) Classification & Labelling Inventory, this substance is currently not classified as hazardous and does not require GHS hazard pictograms. However, this conclusion applies only to non-nanoform, conventional MoS₂ with particle size >1μm. Under the EU CLP Regulation (EC No 1272/2008), nano-scale MoS₂ (particle size <100nm, specific surface area >60m²/g) must be classified as UN 3077 (substance hazardous to the environment) with a complete SDS required.

Global Regulatory Compliance Requirements

Under the EU REACH Regulation, MoS₂ as a non-dangerous substance requires registration when annual production or import volume ≥1 ton. In October 2024, ECHA updated its assessment list for molybdenum and related substances, placing high-purity MoS₂ on the "low-priority concern substance" list, meaning registrants need not provide additional test data but must periodically update use information in registration dossiers.

In the United States, CAS number 1317-33-5 is listed on the TSCA Inventory of existing chemical substances, allowing free manufacture, import, and processing under TSCA compliance. In March 2025, the EPA released new TSCA risk assessment guidelines that did not include MoS₂ among the 50 priority chemicals for assessment.

In China, MoS₂ is listed on the exemption list of the Catalog of Hazardous Chemicals (2015 Edition) and is not classified as a hazardous chemical. However, under the Environmental Management Registration Measure for New Chemical Substances (MEE Order No. 12), nano-scale MoS₂ requires environmental management registration as a new chemical substance, while conventional forms require no additional approval.

SDS and Transport Classification

The SDS for MoS₂ should be prepared following GHS Rev.10 standards, covering 16 sections. Particular attention should be paid to: Section 9 "Physical and Chemical Properties" specifying density 4.80-5.06g/cm³, Mohs hardness 1.0-1.5, melting point 1185°C (decomposition); Section 10 "Stability and Reactivity" noting oxidation above 350°C in air producing molybdenum trioxide (MoO₃) and sulfur dioxide (SO₂); Section 13 "Disposal Considerations" indicating waste should be handled as general industrial solid waste.

For transport classification, conventional MoS₂ (particle size >1μm) is not classified as UN dangerous goods and may be transported as ordinary chemicals. Nano-scale MoS₂ must be declared under UN 3077 Class 9 (Environmentally hazardous substance, solid, N.O.S.), with air transport single-package maximum net weight limits of 30kg for passenger aircraft and 100kg for cargo aircraft.

Common Compliance Issues in Practice

In actual trade, CAS number accuracy directly affects customs clearance efficiency. A 2025 industry survey showed approximately 12% of molybdenum-related exporters confused the CAS numbers for MoS₂ (1317-33-5) and MoO₃ (1313-27-5) during customs declaration, causing average clearance delays of 48 hours. Another common issue is the failure to distinguish compliance differences between conventional and nano forms in SDS, where some companies use conventional MoS₂ SDS for nano-scale product exports, creating compliance risks.

Purchasers should verify CAS number accuracy on supplier-provided COA (Certificate of Analysis) and confirm product form consistency with SDS descriptions. For nano-scale products, suppliers should provide additional nano-material safety data sheets (nano-SDS) to meet EU nano-material notification requirements implemented in 2025.

Conclusion

CAS number 1317-33-5 serves as the "ID card" for MoS₂ in global trade. Accurately understanding its compliance implications across different regulatory frameworks helps reduce trade risks and improve customs clearance efficiency. As nanomaterial regulation tightens worldwide, distinguishing compliance requirements between conventional and nano forms will become an increasingly important aspect of MoS₂ supply chain management.

---

**Tags**: MoS2 CAS number, 二硫化钼CAS号, CAS 1317-33-5, chemical identification, REACH compliance, TSCA, GHS classification, SDS safety data sheet, nano-scale MoS2, compliance requirements