**Exhibit 21.1**

**SUBSIDIARY LIST**
|     | ** ** | Name of Subsidiary                              | ** ** | **Country or  State of Incorporation  or Reorganization** |
|-----|------------|-------------------------------------------------|------------|-----------------------------------------------------------|
| 1.  |       | Delpen Corporation                              |       | Delaware                                                  |
| 2.  |       | PQ Systems Incorporated                         |       | Pennsylvania                                              |
| 3.  |       | Commercial Research Associates, Inc.            |       | Pennsylvania                                              |
| 4.  |       | Philadelphia Quartz Company                     |       | Pennsylvania                                              |
| 5.  |       | PQ Export Company                               |       | Delaware                                                  |
| 6.  |       | PQ International, Inc.                          |       | Pennsylvania                                              |
| 7.  |       | PQ Asia Inc.                                    |       | Delaware                                                  |
| 8.  |       | PQ Hollow Spheres Limited                       |       | United Kingdom                                            |
| 9.  |       | Zeolyst International                           |       | Kansas (50%)                                              |
| 10. |       | Potters Industries Inc.                         |       | New York                                                  |
| 11. |       | PQ Holding, Inc.                                |       | Delaware                                                  |
| 12. |       | PQ Austria GmbH                                 |       | Austria                                                   |
| 13. |       | Interminglass Sp. Z.o.o.                        |       | Poland                                                    |
| 14. |       | Potters-Ballotini Co., Ltd.                     |       | Japan                                                     |
| 15. |       | Potters (Thailand) Limited                      |       | Thailand (75%)                                            |
| 16. |       | PQ Chemicals Asia Limited                       |       | Thailand                                                  |
| 17. |       | PQ Canada Company                               |       | Nova Scotia, Canada                                       |
| 18. |       | PQ Silicates Ltd.                               |       | Taiwan (50%)                                              |
| 19. |       | Aekyung-PQ Advanced Materials Co., Ltd.         |       | South Korea (50%)                                         |
| 20. |       | PQ Europe ApS                                   |       | Denmark                                                   |
| 21. |       | NSL Potters Canada Company                      |       | Nova Scotia, Canada                                       |
| 22. |       | PQ Australia Pty. Limited                       |       | Australia                                                 |
| 23. |       | Potters Ballotini Ltd.                          |       | United Kingdom                                            |
| 24. |       | Potters Industries Pty. Ltd.                    |       | Australia                                                 |
| 25. |       | Potters Ballotini S.A.S                         |       | France                                                    |
| 26. |       | Ballotini Panamericana S.A.                     |       | Mexico                                                    |
| 27. |       | Potters Industrial Limitada                     |       | Brazil                                                    |
| 28. |       | PQ Nederlands B.V., d/b/a PQ Europe             |       | Netherlands                                               |
| 29. |       | PQ Chemicals (Thailand) Limited                 |       | Thailand                                                  |
| 30. |       | PQ Holdings Mexicana, S.A. de C.V.              |       | Mexico                                                    |
| 31. |       | Potters Canada Partnership d/b/a Potters Canada |       | Ontario, Canada                                           |
| 32. |       | National Silicates Partnership                  |       | Ontario, Canada                                           |
| 33. |       | Silicatos y Derivados, S.A. de C.V. (SIDESA)    |       | Mexico                                                    |
| 34. |       | PQ China (Hong Kong) Limited                    |       | Hong Kong                                                 |
| 35. |       | PQ (Tianjin) Silicates Technology Co., Ltd      |       | China                                                     |
| 36. |       | PQ Potters Europe, GmbH                         |       | Germany                                                   |
| 37. |       | PQ France S.A.S                                 |       | France                                                    |
| 38. |       | PQ Sweden A.B.                                  |       | Sweden                                                    |
| 39. |       | PQ Zeolites B.V.                                |       | Netherlands                                               |
| 40. |       | PQ Norge Silicates AS                           |       | Norway                                                    |
| 41. |       | PQ Silicates II B.V.                            |       | Netherlands                                               |
| 42. |       | PQ International, B.V.                          |       | Netherlands                                               |
| 43. |       | ENAP Management B.V.                            |       | Netherlands                                               |
| 44. |       | PQ Italy S.r.l.                                 |       | Italy                                                     |
| 45. |       | Zeolyst C.V.                                    |       | Netherlands (50%)                                         |
| 46. |       | PQ Finland Oy                                   |       | Finland                                                   |
| 47. |       | Northern Cullet Ltd.                            |       | United Kingdom (92%)                                      |
| 48. |       | PQ Silica VerWaltungs—GmbH i.1.            |       | Germany                                                   |
| 49. |       | PQ Silica GmbH and Co., OHG i.1.                |       | Germany                                                   |

 

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