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        <title>Ecovyst, Inc. Quarterly report pursuant to Section 13 or 15(d)</title>
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            <h3>Quarterly report pursuant to Section 13 or 15(d)</h3>
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                                <a class="menu-item " href="/sec-filings/all-sec-filings/xbrl_doc_only/1673">Cover</a>
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                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1673">Document and Entity Information</a></li>
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                                <a class="menu-item " href="/sec-filings/all-sec-filings/xbrl_doc_only/1674">Financial Statements</a>
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                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1674">CONDENSED CONSOLIDATED STATEMENTS OF INCOME</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1675">CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</a></li>
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                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1677">CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1678">CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS??? EQUITY</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1679">CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</a></li>
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                                <a class="menu-item current" href="/sec-filings/all-sec-filings/xbrl_doc_only/1680">Notes to Financial Statements</a>
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                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1680">Background and Basis of Presentation</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1681">New Accounting Standards</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1682">Revenue from Contracts with Customers</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1683">Fair Value Measurements</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1684">Accumulated Other Comprehensive Income</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1685">Sale of Product Line</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1686">Goodwill</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1687">Other Operating Expense, Net</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1688">Inventories, Net</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1689">Investments in Affiliated Companies</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1690">Property, Plant and Equipment</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1691">Leases</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1692">Long-term Debt</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1693">Financial Instruments</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1694">Income Taxes</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1695">Benefit Plans</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1696">Commitments and Contingent Liabilities</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1697">Reportable Segments</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1698">Stock-Based Compensation</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1699">Earnings per Share</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1700">Supplemental Cash Flow Information</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1701">Subsequent Events</a></li>
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                                <a class="menu-item " href="/sec-filings/all-sec-filings/xbrl_doc_only/1702">Accounting Policies</a>
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                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1702">Background and Basis of Presentation (Policies)</a></li>
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                                <a class="menu-item " href="/sec-filings/all-sec-filings/xbrl_doc_only/1703">Notes Tables</a>
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                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1703">Revenue from Contracts with Customers Revenue from Contracts with Customers (Tables)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1704">Fair Value Measurements (Tables)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1705">Accumulated Other Comprehensive Income (Tables)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1706">Goodwill (Tables)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1707">Other Operating Expense, Net (Tables)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1708">Inventories (Tables)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1709">Investments in Affiliated Companies (Tables)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1710">Property, Plant and Equipment (Tables)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1711">Leases (Tables)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1712">Long-term Debt (Tables)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1713">Financial Instruments (Tables)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1714">Benefit Plans (Tables)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1715">Reportable Segments (Tables)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1716">Stock-Based Compensation (Tables)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1717">Earnings per Share (Tables)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1718">Supplemental Cash Flow Information Supplemental Cash Flow Information (Tables)</a></li>
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                                <a class="menu-item " href="/sec-filings/all-sec-filings/xbrl_doc_only/1719">Notes Details</a>
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                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1719">Background and Basis of Presentation (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1720">New Accounting Standards (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1721">Revenue from Contracts with Customers - Disaggregated Revenue (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1722">Revenue from Contracts with Customers - Contract Assets and Liabilities (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1723">Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1724">Accumulated Other Comprehensive Income - Pre-tax and After-tax Components of Other Comprehensive Income (Loss) (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1725">Accumulated Other Comprehensive Income - Change by Component (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1726">Accumulated Other Comprehensive Income - Reclassifications out of AOCI (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1727">Sale of Product Line (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1728">Goodwill (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1729">Other Operating Expense, Net (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1730">Inventories (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1731">Investments in Affiliated Companies - Ownership Percentage (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1732">Investments in Affiliated Companies - Summarized Income Statement (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1733">Investments in Affiliated Companies - Narratives (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1734">Property, Plant and Equipment (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1735">Property, Plant and Equipment - Narratives (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1736">Leases - Narratives (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1737">Leases - Right-of-Use Lease Assets and Lease Liabilities (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1738">Leases - Remaining Average Weighted Average Lease Term and Discount Rate (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1739">Leases - Lease Maturity Schedule - ASC 842 (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1740">Leases - Lease Maturity Schedule - ASC 840 (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1741">Leases - Other Lease Information (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1742">Long-term Debt (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1743">Long-term Debt - Narratives (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1744">Financial Instruments - Narratives (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1745">Financial Instruments - Fair Value (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1746">Financial Instruments - Effect on Other Comprehensive Income (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1747">Financial Instruments - Cash Flow Hedge Impact on Income Statement (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1748">Financial Instruments - Net Investment Hedge Impact on AOCI (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1749">Income Taxes (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1750">Benefit Plans - Net Periodic Pension Expense Benefit (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1751">Reportable Segments  - Summary Financial Information by Reportable Segment (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1752">Reportable Segments  - Reconciliation of Net Income to Segment Adjusted EBITDA (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1753">Stock-Based Compensation - Narratives (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1754">Stock-Based Compensation - Schedule of RSU and PSU Activity (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1755">Earnings per Share - Reconciliation from Basic to Diluted Weighted Average Shares Outstanding (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1756">Earnings per Share - Calculation of Basic and Diluted Earnings per Share (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1757">Earnings per Share - Anti-dilutive Shares (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1758">Supplemental Cash Flow Information - Supplemental Cash Flow Information (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1759">Supplemental Cash Flow Information - Cash and Restricted Cash Reconciliation (Details)</a></li>
                                                                            <li><a href="/sec-filings/all-sec-filings/xbrl_doc_only/1760">Subsequent Events (Details)</a></li>
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                                            </ul>
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                <h4>Subsequent Events</h4>
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