DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claim(s) 1-17 is/are rejected under 35 U.S.C. 103 as being unpatentable Andersen et al. US 20190084831(previously cited), in view of WO2022265647 (newly cited).
Regarding claim 1, Andersen et al. teaches generating ammonia gas from liquid ammonia and then cracking the ammonia gas to yield a mixture of hydrogen and nitrogen (Abstract). The reference teaches power generation from combustion of hydrogen (Para [0011]). The reference teaches cracking ammonia using a catalyst at a dissociation temperature to yield hydrogen and nitrogen (Para [0017]). The reference further teaches that the composition of the hydrogen and nitrogen mixture is adjusted by purification techniques, including pressure swing adsorption (Para [0030]).
The difference between the invention of Andersen et al. and that of claim 1 is that claim 1 requires separating the hydrogen and nitrogen mixture into a high-pressure hydrogen stream and a first hydrogen depleted tail gas stream in a first PSA, then compressing the first hydrogen depleted tail gas stream and recycling it back to the PSA.
WO’5647 teaches hydrogen from an ammonia cracking process (Abstract). The reference teaches that the cracked ammonia gas is purified in a first PSA and a portion of the first PSA tail gas is recycled as fuel to reduce the carbon intensity of the hydrogen product (See Fig. 4). A compressor (K301) is shown in this figure for the tail stream (line 54) that is recycled back to the PSA.
Before the effective filing date of the claimed invention it would have been obvious for a person of ordinary level of skill in the art to compress and recycle a portion of the tail gas back to the PSA, in the inventio of Andersen. One would be motivated to do so to improve hydrogen recovery as taught by WO’5647 (Pg. 7, lines 3-8).
Regarding claims 2, WO’5647 teaches compressing the tail gas from the first PSA to purify the compressed tail gas in a second PSA to produce a second PSA tail gas and a second hydrogen gas stream (Pg. 7, lines 15-20). This reference further teaches that a further portion of the first or second PSA tail gasses can be processed in a separator and recycled back for further processing in the PSA devices (Pg. 8, lines 12-15).
Before the effective filing date of the claimed invention it would have been obvious for a person of ordinary skill in the art to further process the recycled tail gas in a second PSA before recycling it back to the first PSA of WO’5647. It is considered obvious to apply a known technique to a known device or method to yield a predictable result, such as for further extracting hydrogen (See MPEP §2141 III. (D)).
Regarding claim 3, the WO’5647 reference teaches dividing the tail gas 18 from the first PSA into streams 56 and 54 (See Fig. 4 and Pg. 16, lines 4-11). Only stream 54 is sent to the compressor and recycled back to the PSA (See Fig. 4). Since the tail gas comprises the nitrogen, this division is considered as removing a nitrogen portion from stream 54. Thus the reference teaches compressing a second portion of the tail gas stream.
Regarding claim 4, before the effective filing date of the claimed invention it would have been obvious for a person of ordinary level of skill in the art to recycle the stream from the second PSA with the high hydrogen pressure back to the first PSA for hydrogen recovery. One would be motivated to do so because this stream has hydrogen, as opposed to the tail gas from the second PSA.
Regarding claim 5, the WO’5647 reference teaches that the product hydrogen from the second PSA device (line 68) is combined with the hydrogen product (line 30) from the first PSA device (26) to form a combined hydrogen product gas (line 70) . See Pg. 16, lines 15-18. This is considered as “recovering” the second high pressure hydrogen stream.
Regarding claim 6, the Andersen et al. reference teaches recovering any unconverted ammonia gas by using a water scrubber (Para [0029]). This is considered as water washing to remove ammonia.
Regarding claim 7, WO’5647 does not teach that the tail gas is recycled to a water washing vessel.
However, Andersen teaches that unconverted ammonia can be recovered in a water scrubbing step (considered as a water washing step; See Para [0029]).
At the time of filing it would have been obvious for a person of ordinary level of skill in the art to divert the second hydrogen depleted stream from the bottom of the second PSA of WO’5647, into the water washing step of Andersen. One would be motivated to do so in an effort to recover any remaining ammonia.
Regarding claims 8 and 9, Andersen teaches combusting a portion of the cracked effluent comprising hydrogen and nitrogen recovered from ammonia cracking for heating the ammonia cracking (Para [0036]).
The combination of Andersen and WO’5647 references does not teach using the first hydrogen depleted tail gas or the second hydrogen depleted tail gas as a heat source.
At the time of filing it would have been obvious for a person of ordinary to combust the first or the second hydrogen depleted gas stream in the power generation system of Andersen to generate heating for the ammonia cracking. Andersen teaches the utilization of hydrogen and nitrogen for combustion yields a continuous and reliable power supply (Para [0035]).
Regarding claims 10 and 11, since complete conversion and separation is not expected in any chemical reaction, it would be expected that some raw material ammonia remains in these claimed streams.
Regarding claim 12, the Andersen et al. reference teaches preheating the ammonia with the cracked effluent in exchanger 1 (See Para [0070] and Fig. 1).
Regarding claims 13 and 14, the WO’5647 is silent on the pressure of the stream exiting the first and second PSA units. However, the reference indicates that the PSA operating pressures are between 1.1-40 bar MPa (Pg. 7, lines 10-13). This would indicate that the pressures of the gases leaving the first and second PSA would be within this range. The range of the reference is overlapping with the claimed ranges.
Overlapping ranges are considered obvious (MPEP §2144.05 I).
Regarding claim 15, the Andersen et al. reference teaches that the cracked effluent is cooled to 40-300ºC (Para [0045]). This range is broader than the claimed range and overlaps with the claimed range. The effluent is cooled to preheat the incoming ammonia into the cracker (See preheater 1 and Para [0070]).
At the time of filing it would have been within the skill of a person of ordinary level of skill in the art to determine a suitable or optimal temperature to cool the effluent the hydrogen. Cooling the effluent further to the lower end of the range in Andersen would be equivalent to preheating the ammonia to a higher temperature and thus requiring lesser heat/energy in the ammonia cracker. Thus the temperature the effluent is cooled to a result effective variable and can be optimized without undue experimentation.
Regarding claim 16, the Andersen teaches combusting a portion of the cracked effluent comprising hydrogen and nitrogen recovered from ammonia cracking for heating the ammonia cracking (Para [0036]). The combination of Andersen and WO’5647 references does not teach using the first hydrogen depleted tail gas or the second hydrogen depleted tail gas as a heat source.
At the time of filing it would have been obvious for a person of ordinary to combust the first or the second hydrogen depleted gas stream in the power generation system of Andersen to generate heating for the ammonia cracking. Andersen teaches the utilization of hydrogen and nitrogen for combustion yields a continuous and reliable power supply (Para [0035]).
A further difference is that the amount of heat duty replaced is not taught.
At the time of filing it would have been within the skill in the art to determine a suitable or optimal amount of heat duty that the hydrogen/nitrogen mixture would provide for the ammonia cracking. The amount of heat duty provided would replace the heat required from other sources to crack the ammonia. Thus making this a result effective variable that can be optimized without undue experimentation.
Regarding claim 17, the percentage of hydrogen recovered in the cracked effluent is not disclosed in Andersen or WO’5647. However, the Andersen et al. reference teaches that the composition of the hydrogen and nitrogen mixture can be adjusted in the cracked effluent utilizing purification techniques such as pressure swing adsorption (Para [0046]).
At the time of filing it would have been within the skill of a person of ordinary level of skill in the art to determine a suitable or optimal hydrogen recovery percentage. The operating conditions of the PSA would directly control how much hydrogen is separated from the cracked effluent. The amount of hydrogen is thus a result effective variable and can be optimized without undue experimentation.
Response to Arguments
Applicant’s arguments, see Pg. 2, filed 02/17/2026, with respect to Zhong et al. US 20190275460 have been fully considered and are persuasive. The rejection of claims 1-17 in view of Zhong has been withdrawn.
Conclusion
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/SYED T IQBAL/Examiner, Art Unit 1736
/WAYNE A LANGEL/Primary Examiner, Art Unit 1736
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