C01B 21/20
Nitrogen oxides
Official title: Nitrogen oxides; Oxyacids of nitrogen; Salts thereof
C01B21/20 (Nitrogen oxides) appears on 728 US grants and 678 published applications in this corpus.
Search patents in C01B- Granted patents
- 728
- Published applications
- 678
- Assignees
- 425
- Inventors
- 1,476
- Latest grant
- 22 Sep 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1976 | 22 | 0 |
| 1977 | 19 | 0 |
| 1978 | 24 | 0 |
| 1979 | 14 | 0 |
| 1980 | 11 | 0 |
| 1981 | 16 | 0 |
| 1982 | 11 | 0 |
| 1983 | 12 | 0 |
| 1984 | 12 | 0 |
| 1985 | 11 | 0 |
| 1986 | 4 | 0 |
| 1987 | 9 | 0 |
| 1988 | 4 | 0 |
| 1989 | 9 | 0 |
| 1990 | 6 | 0 |
| 1991 | 6 | 0 |
| 1992 | 14 | 0 |
| 1993 | 13 | 0 |
| 1994 | 11 | 0 |
| 1995 | 8 | 0 |
| 1996 | 3 | 0 |
| 1997 | 12 | 0 |
| 1998 | 7 | 0 |
| 1999 | 5 | 0 |
| 2000 | 9 | 0 |
| 2001 | 12 | 2 |
| 2002 | 7 | 6 |
| 2003 | 10 | 15 |
| 2004 | 8 | 15 |
| 2005 | 8 | 10 |
| 2006 | 7 | 9 |
| 2007 | 8 | 6 |
| 2008 | 5 | 11 |
| 2009 | 10 | 13 |
| 2010 | 8 | 25 |
| 2011 | 10 | 16 |
| 2012 | 15 | 33 |
| 2013 | 23 | 32 |
| 2014 | 22 | 36 |
| 2015 | 26 | 35 |
| 2016 | 24 | 20 |
| 2017 | 35 | 34 |
| 2018 | 15 | 37 |
| 2019 | 29 | 35 |
| 2020 | 26 | 36 |
| 2021 | 29 | 35 |
| 2022 | 23 | 37 |
| 2023 | 26 | 45 |
| 2024 | 25 | 50 |
| 2025 | 24 | 47 |
| 2026 | 21 | 38 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Subgroups
Granted patents
- C01B 21/24Nitric oxide446
- C01B 21/38Nitric acid154
- C01B 21/50Nitrous acid52
- C01B 21/22Nitrous oxide49
- C01B 21/36Nitrogen dioxide49
- C01B 21/48Methods for the preparation of nitrates in general29
- C01B 21/203Preparation of nitrogen oxides using a plasma or an electric discharge27
- C01B 21/206Nitric anhydride3
All 9 subgroupsShow fewer
Recent patents
- Solid-gas reaction to generate nitroxyl (HNO) in the gas phase22 Sep 2026US 12,740,999 B2Consejo Nacional De Investgaciones Cientficas Y Tecnicas Conicet
- Gauzes having a tertiary structure for the catalytic conversion of fluids15 Sep 2026US 12,734,513 B2
- Nitric oxide water generation system having purifying part for automatically purifying water in reaction chamber8 Sep 2026US 12,729,118 B2
- Method for the synthesis of nitrogen oxides and nitric acid in a thermal reactor25 Aug 2026US 12,715,769 B2Nitrocapt AB
- Methods for oxidizing a nitrogen oxide to nitrate25 Aug 2026US 12,715,770 B2University of Miami
- Method for selectively recovering volatile pt or pd10 Sep 2026US 2026/0265057 A1Yara International Asa
- Free-flowing food grade sodium nitrite and production method thereof20 Aug 2026US 2026/0242222 A1Deepak Nitrite Limited
- Renewable power to x module based on ozonation assisted electrochemical energy conversion reaction20 Aug 2026US 2026/0242960 A1NewSouth Innovations Pty Limited
- Apparatus for production of ammonium nitrate from nitric acid and ammonia13 Aug 2026US 2026/0233190 A1thyssenkrupp AG
- Nitric oxide generation process controls13 Aug 2026US 2026/0233997 A1Third Pole, Inc.
Most cited
By later US patents
- Method and apparatus for the generation of nitric oxide499US 5,827,420 AWorld Precision Instruments, Inc. · 1998
- Apparatus for on-site production of nitrate ions409US 7,514,058 B1The Lata Group, Inc. · 2009
- Nanotechnology for engineering the performance of substances140US 6,531,704 B2NanoProducts Corporation · 2003
- Method and apparatus for nitric oxide generation135US 7,040,313 B2CyTerra Corporation · 2006
- Method and device for transforming chemical compositions120US 6,214,195 B1Nanomaterials Research Corporation · 2001