Preparation of Cu( І )Y from binary Cu(II) precursors and its CO adsorption performance

Separation and puri�cation of CO is an important chemical process. Adsorption is competitive due to its e�cient operation, low energy and matured technology. For CO adsorption, the capacity and selectivity of the adsorbent is the key factor to determine the e�ciency. In this paper, C2H5OH was used as the dispersing agent, CuCl2 and Cu(CH3COO)2 were used as the precursors mixing with HY molecular sieve, then followed by activation at different temperatures to prepare CO adsorbents. The maximum CO adsorption capacity was 42 mL/gHY, which was 28.4 % higher than that of the adsorbent prepared with water as the dispersing agent. The adsorbents were characterized by BET, XRD, XRF, XPS and TG-MS. It was revealed that Cu(II) can be reduced to Cu(I) at 290 ℃ and highly dispersed on surface of HY. Ion exchange occurred between HY molecular sieve and Cu((I) salts, and Cu (I) Y came into being. Compared with Cu(II), Cu and even CuCl/HY, Cu (I) Y had the best CO adsorption performance.


INTRODUCTION
Carbon monoxide (CO) is well known as an important chemical raw material.The synthesis of carbonbased chemicals such as acetic acid, dimethyl carbonate, acetic anhydride, methyl formate and isocyanate all require high-purity CO as the raw materials [1][2][3] .CO is a toxic air pollutant that has brought up environmental problems such as acid rain, ozone depletion and climate change, which can lead to signi cant health risk 4,5 .Moreover, slight CO is a harmful substance in some industrial gas, which can deactivate the active sites of catalyst, especially for some precious metal catalysts such as Pt et al. 6,7 .Therefore, the separation and puri cation of CO from gas mixtures is necessary due to its industrial bene ts and environmental effects.
There are many methods to separate CO from mixed gas such as cryogenic distillation, absorption and adsorption [8][9][10] .In theory, separation is an energy-consuming process because the second law of thermodynamics does not favor it.Compared with the traditional technologies, adsorption is competitive due to its low energy cost, e cient operation and matured technology 11,12 .In adsorption separation, the commonly used carriers are molecular sieve, activated carbon, synthetic resin, activated alumina and other porous carriers [13][14][15] .Molecular sieve has been widely considered as a promising adsorbent material for CO separation and puri cation due to its good thermal stability, excellent adsorption selectivity, large speci c surface area and narrow pore size distribution 16,17 .For CO adsorption, the capacity and selectivity of the adsorbent is the key factor to determine the e ciency.Many adsorbents incorporated by Cu(І) or Ag(І) have received much attention because they can capture CO molecules through πcomplexation 18, 19 .Compared with physical adsorption, the π-complexation bonds are generally stronger than electrostatic and Van der Waals interactions, so it shows higher selectivity.Compared with general chemisorption, its relative weak π-complexation force make it easy to regenerate 19 .In particular, Cu (І) adsorbent, due to its cheap and easy availability, is regarded as a promising adsorbent, has been widely studied in recent years.
Traditionally, adsorbent was made by single copper precursors.As early as the 1970s, the United Carbon Corporation (UCC, US) had reported a patent about CO adsorbent prepared by ion exchange of Cu + or Ag + , but its CO adsorption performance was poor 20 .Based on a general principle that compounds tend to spontaneously disperse on the high surface supports to form a monolayer, Xie et al. prepared CuCl/Y adsorbent by a thermal treatment of a mixture of CuCl and Y molecular sieve.The results showed that CuCl dispersed uniformly on Y molecular sieve at atomic level and the adsorbent was widely used in industry 17,21 .Takahashi et al. exchanged excess Cu (NO 3 ) 2 solution with NaY for 24 hours at room temperature and reduced Cu 2+ to Cu + using different reducing agents such as ammonia or CO, followed by activation at 300-450 ℃ under He 22 .Sun et al. used NaY molecular sieve as carrier and CuCl 2 as precursor, and prepared CuCl/Y under mild reduction of glucose 23 .It was found that the separation performance and the stability of the adsorbent were good.
The application of single copper precursor was restricted due to their instability or insolubility.In order to introduce more Cu(I) on molecular sieve, multiple attempts have been made.Using binary Cu(II) precursors was a potential solution to solve the problems such as low-loading and easy oxidation.Some researchers had already made some explorations 5 .A CuCl/AC adsorbent was made by a facile route of physically mixing CuCl 2 and Cu(HCOO) 2 powder with activated carbon (AC), followed by heating at 533 K under vacuum, and the result was good.
It is well known that CuCl 2 and Cu(CH 3 COO) 2 are more stable and cheaper than CuCl.In this paper, CO adsorbent was prepared using binary Cu(II) precursors, HY molecular sieve as carrier, and different dispersing agents.O ( the total amount of Cu 2+ was certain were dissolved in a solvent (deionized water or C 2 H 5 OH).Secondly, the pretreated HY was added to the above solution, and the hydrothermal ion exchange was performed at different temperature for 12 h.Thirdly, The sediment was separated via centrifugation.Finally, the sediment was dried and activated in a tube furnace under Ar ow.The experiments were conducted by heating the sediments from room temperature to the nal temperatures at rate of 2 ºC /min, followed by an isothermal treatment for 4 h and nally cooling down to room temperature.

CO adsorption/regeneration measurments
Dynamic adsorption of CO was evaluated with a xed bed, as shown in Figure 1. 1 g tablet sample was put into a quartz tube with a diameter of 10 mm and a length of 38 mm.The adsorption temperature was maintained at 30 ºC by a electric furnace temperature controller and a cryogenic coolant circulation tank.
The N 2 ow containing 1 % CO passed through the xed bed at a ow rate of 150 mL/min.The adsorbed gas was detected by KE200-U multi-component gas analyzer (Xi'an Kepeng Electrical Equipment Co., Ltd.) with an accuracy of 1 ppm and a range of 0-1000 ppm.In the breakthrough experiment, the zerotime was determined by the blank test.The breakthrough point was set at the concentration of each adsorbent in outlet gas reached 5 % of the component in the feed.The tail gas was vented to the atmosphere after absorption.Regeneration was performed with N 2 as the regeneration gas.The relative experimental error of the estimated amounts was lower than ± 5 %.

CO adsorption isothermal
The adsorption isotherms of CO were measured by a corrosive gas adsorption analyzer BSD-PMC ( Beishide Instrument, China ).Approximately 0.1 g of the sample was degassed at 523 K for 3 h in vacuum.The adsorption capacity of the adsorbent were obtained by a static volumetric method at 30 ℃ with a error of ± 1 %.

Characterization
The crystalline structures of Cu(І)Y adsorbents were examined by powder X-ray diffractometer ( EMPYREAN, Holland ).The X-ray diffractometer used Cu Ka radiation.The tube voltage and current were 40 kV and 30 mA, respectively.For all samples, the 2q angle was scanned from 5° to 60° with a scanning speed of 5°/min and 0.02° per step.The XRD patterns were analyzed using MDI Jade software package.
Nitrogen adsorption-desorption isotherms ( BET ) were obtained at 77 K using ASAP-2460 instrument.The samples were outgassed at 250 ℃ for 3 h in a dynamic vacuum before the adsorption isotherm was determined.The PSD was obtained from density functional theory( DFT ) method.The total pore volume ( Vt ) was generated according to the N 2 adsorption at the relative pressure ( P/P 0 ) of 0.99.Micropore volume ( V mic ), Micropore volume ( V mic ), micropore ratio surface ( S mic ) and external surface area ( S ex ) were obtained by the t-plot method.

XRF experiments
The main elemental components of the prepared adsorbents was tested by X-ray uorescence spectroscopy (XRF).In this paper, Thermo Scienti c ARL Perform'X X-ray uorescence spectrometer was used to test the powder adsorbents.

XPS experiments
The chemical state of copper in CO adsorbents were investigated by X-ray photoelectron spectrometer ( XPS ).XPS analysis were performed by XSAM800 instrument from KRATOS, UK.With Al Kα monochromatic radiation ( 1486.6 eV ) and a high-vacuum chamber, the anode was operated at 120 W, and the analyzer was operated at a constant narrow scan pass energy of 30 eV.The XPS analysis was calibrated by the C1s peak at 284.6 eV.Due to the coexistence of Cu(І) and Cu(II), the XPS spectra were deconvoluted using the casa XPS software and the peak position and peak region were determined.

TG-MS experiments
In order to explore the mechanism of adsorbent in preparation, the thermogravimetric and mass spectrometric experiments ( TG-MS ) were conducted on NETZSCH STA449F3-QMS403 Aeolos Quadro analyzer coupled with a mass spectrometer.About 14 mg of un-activated sample were placed in a ceramic crucible.The samples were heated from room temperature to 290 ℃ with a heating rate of 5 ℃/min followed by an isothermal period for 1 h.The experiments used high purity Ar as carrier gas at a constant ow rate of 50 mL/min.

CO adsorption of prepared adsorbents
Figure 2 showed CO adsorption capacities of the prepared adsorbents.According to the literature 17, 21, 24- 26 , the dispersion of copper in molecular sieve was a key factor affecting CO adsorption.Figure 2a summarized the effect of solvent in solvothermal process on adsorbent performance.When using water as the solvent, the CO adsorption capacity of the prepared adsorbents were 1.14 mL/g, 9.87 mL/g and 4.79 mL/g respectively.However, when using C 2 H 5 OH as the solvent, the adsorption capacity of the prepared adsorbents signi cantly improved, which were 1.35 mL/g, 10.00mL/g and 12.67 mL/g respectively.The CO adsorption capacity of the adsorbent prepared with C 2 H 5 OH as solvent was 28.4 % higher than that of the adsorbent prepared with water as solvent.It indicated that, in solvothermal process, the solvent played an important role in ion exchange and ion distribution.Different solvent had different solubility, polarity, surface tension and volatility, which resulted in a different presence state and mobility of copper salts in solvothermal process.C 2 H 5 OH is a good dispersing agent in chemical industry.
When C 2 H 5 OH was used as the solvent, it would enhance the mass transfer and distribution of the copper salts in HY molecular sieve.So, C 2 H 5 OH was chosen as the solvent in solvothermal process in this paper.
Figure 2b showed the effect of solvothermal temperature on adsorbent performance.In solvothermal process, with increasing solvothermal temperature, the thermal motion of the ions in solution became more active, which enhance the mass transfer and ion exchange in solvothermal process.Therefore, high solvothermal temperature was bene cial to improve the CO adsorption performance of the adsorbent.
Considering the volatility of the solvent, 70 ℃ was chosen as the solvothermal temperature.
Figure 2c showed the effect of activation temperature on adsorbent performance.Before activation, the adsorbent had a very low CO adsorption capacity, as listed in Figure 2c.According to the literature, Cu(II) almost had no contribution to CO adsorption, while Cu(І) was recognized as the preferred adsorbent form, which had strong a nity to CO in CO adsorption [27][28][29] .In order to change the valence state of copper from Cu 2+ to Cu + , it was necessary to activate the sediments.The activation temperature directly affected the adsorbent performance because it deternined the amount of Cu(І) active sites generated.With the increase of activation temperature, the CO adsorption capacity of the prepared adsorbents increased obviously.When the activation temperature was 290 ℃, the CO adsorption capacity of the adsorbent reached the highest, indicating more Cu(I) active sites generated.When the activation temperature increased further, the CO adsorption capacity of the adsorbent did not increase, but decreased gradually.The reason may exist in two aspects: one was that higher temperature turned Cu(I) into Cu, which had low CO adsorption ability [30][31][32] ; The other was that higher temperature may cause the aggregation of the active sites.So, the activation temperature was chosen as 290 ℃. 2d showed the effect of Cu(CH 3 COO) 2 •H 2 O/CuCl 2 •2H 2 O mole ratio on adsorbent performance.Even if the total amount of copper was constant, the CO adsorption capacity of the adsorbents were quite different.Whether water or C 2 H 5 OH as the solvent, it was obvious that the prepared adsorbent had a very low CO adsorption capacity when using a single Cu(CH 3 COO) 2 or CuCl 2 as the copper precursor.The reasons were as follows: 1) Very little Cu 2+ loading onto HY molecular sieve through ion exchange; 2) Very little amount of Cu 2+ converted into Cu + during activation process.More explore was needed.

It was important to choose an appropriate mole ratio of CuCl
With binary copper salts as the precursors, the experimental results were interesting.When using water as the solvent, the optimal Cu (CH 3 COO) 2 •H 2 O / CuCl 2 •2H 2 O mole ratio was 1/1, as listed in Figure 2a.Xue had revealed the mechanism of equal mole of Cu(HCOO) 2 and CuCl 2 impregnating on active carbon 5 : The divalent copper was reduced to monovalent copper via self-redox reactions, and the monovalent copper was highly dispersed on the surface of AC.When Cu (HCOO) 2 / CuCl 2 mole ratio was small, the decomposition product Cu (HCOO) 2 was not enough to reduce the CuCl 2 to monovalent copper, resulting in less active sites on the adsorbent, so the CO adsorption capacity was small; When Cu (HCOO) 2 / CuCl 2 mole ratio was 1, Cu (HCOO) 2 was appropriate to reduce the CuCl 2 to monovalent copper, resulting in much active sites on the adsorbent, so the CO adsorption capacity was large; When the molar ratio of Cu (HCOO) 2 / CuCl 2 was greater than 1, a part of Cu (HCOO) 2 reduced CuCl 2 to monovalent copper, producing the active site, and the excess Cu (HCOO) 2 played a small role in CO adsorption, so the adsorption capacity of CO was reduced, as shown in (1).2e.The results showed that as the total copper amount increased from 1.75 mmol Cu 2+ /gHY to 7.0 mmol Cu 2+ /gHY, the CO adsorption capacity increased from 6.70 mL/g to 15.15mL/g.However, it gradually decreased with the further increase of the total copper amount.Adsorption occurs at the active sites of an adsorbent.At low copper loading, optimal CO adsorption capacity may not be reached due to lack of active sites, while excess copper loading may block the pore entrances of the Y molecular sieve to decrease the surface area and CO adsorption capacity.Therefore, the optimal copper loading was 7.00 mmol Cu 2+ /gHY.
An adsorption isotherm can provide information on the adsorption capacity of an adsorbents.Figure 2f illustrated the CO adsorption/desorption isotherms.It was a typical type I isotherm, suggesting the strong interaction between CO and the adsorbent via a π-complexation.In Figure 2f, the plateau for the adsorbent (7.0 mmol Cu 2+ /gHY) was reached very near the value of 42 mL/g, while for the adsorbent (3.5 mmol Cu 2+ /gHY) , the plateau was reached at about 30 mL/g.That was, the adsorbent with 7.0 mmol Cu 2+ /gHY contributed more active sites than the adsorbent with 3.5 mmol Cu 2+ /gHY.
The stability of CuY was tested in the xed bed.The regeneration was performed at 100 ℃ at atmospheric pressure at N 2 ow rate of 100 mL/min.After 5 times of adsorption and regeneration, the adsorption capacity was almost unchanged, indicating that the character of the adsorbents were stable.

Adsorbents characterization
Figure 3 illustrated the N 2 adsorption-desorption equilibrium isotherms ( BET ) of HY molecular sieve and the adsorbents prepared with different amount of copper loading at 77K.According to IUPAC, the adsorption-desorption isotherms of N 2 all exhibited the typical type І isotherm that was obtained on micro-porous materials, where mono-layers adsorption were formed on the surface 33,34 .From Figure 3a, it was found that, with the increase of copper loading on the adsorbents, their N 2 adsorption amounts apparently decreased.The BET surface area, pore volume and average pore diameters of HY molecular sieve and the adsorbents prepared with different amount of copper loading were summarized in Table 2.
With the copper loading increasing, the speci c surface area and pore volume of the molecular sieve decreased gradually because the copper loaded on the cage of the Y molecular sieve.For the typical type І isotherm, the surface area of the sample was much smaller than the surface area of the hole volume, and the adsorption capacity was controlled by the volume of the hole.As for the CO adsorption, the adsorption of CO was not only closely related to its speci c surface area, but also to the amount of active sites.For the copper loading on the molecular sieve, on the one hand, it increased the number of CO adsorption active sites, but on the other hand, it reduced the speci c surface area of the molecular sieve.This conclusion was consistent with the experimental results, as shown in Table 1.It could be observed that the CO adsorption capacity increased from 0.12 mL/g to 15.15 mL/g with the increase of copper loading amount from 0 to 7.0 mmol Cu 2+ /gHF, which was attributed to the π complexation between CO and Cu(І) active sites of the adsorbents.The CO adsorption/desorption isotherms of the adsorbents were in good agreement with the gure of N 2 adsorption-desorption isotherms, indicating that all the micropores were all accessible to CO.When the copper loading amount increased from 7.0 mmol Cu 2+ /gHF to 10.5 mmol Cu 2+ /gHF, the CO adsorption capacity decreased slightly because much copper active site reduced the speci c area of the Y molecular sieve.
Figure 4a illustrated the XRD patterns of HY molecular sieve and the adsorbents activated at different temperatures.Compared with HY molecular sieve, the crystalline structure of the adsorbents were well maintained after activated at different temperatures 35 .Before activation, though there were Cu (CH 3 COO)  5 , and the possible reason was that the loading methods were different in adsorbent preparation.Compared with the dipping method by Xue et al., the solvothermal method made the copper salts disperse on HY molecular sieve more evenly.After activation at 170 ℃, the diffraction peaks of CuCl appeared, which displayed a weak diffraction peak at 28.5 o19,36 , implying more CuCl come into being after 170 ℃ activation.At the same time, some CuCl perhaps changed into Cu(І)Y through ion exchange, the following TG-MS experiments con rmed this opinion.After activation at 290 ℃, the diffraction peaks of CuCl disappeared and only a little of Cu displayed a very weak diffraction peak at 43.3 o , indicating that higher activation temperature perhaps promoted the ion exchange between CuCl and HY to form Cu(І)Y, the following TG-MS experiments con rmed this opinion too.Much Cu(І)Y in adsorbent was bene t to CO adsorption, which was in agreement with the CO adsorption experiment results.At same time, some Cu came into being from CuCl or Cu(І)Y.
According to theory, experiments and literature [37][38][39] , it was supposed that the mechanism of the copper in preparing process was below: It was veri ed that Cu 2+ and Cu had almost no contribution to the CO adsorption of the adsorbents.
Compared with Cu + , Cu(І)Y play a more important role in CO adsorption.XRD results indicated that the multiple copper valences maybe coexistence together in the adsorbents, and more explore was needed.indicating that copper salts overloaded on the molecular sieve.The overloaded copper salts were stacked on the molecular sieve, which had no bene t to CO adsorption.So, the optimum copper loading amount was 7.0 mmol Cu 2+ /gHF, and the conclusion was in accord with experimental results.Cu 2+ /gHF, the weight concentration of copper element and chlorine element increased obviously, while the mole ratio of Cu/Cl was neither 2/1 nor 1/1.It was veri ed that the presence of copper on the HY molecular sieve was very complex.When the copper loading amount was 1.75 mmol Cu 2+ /gHF, the mole ratio of Cu/Cl was 6.92, implying that the majority of the chlorine element changed into HCl via ion exchange with HY molecular sieve and evaporated from the molecular sieve, as shown in (3).The results also indicated that, in the course of the morphological transition of copper, the molecular sieve also played a role.When the copper loading amount was 7.00 mmol Cu 2+ /gHF, the mole ratio of Cu/Cl decreased to 2.15.Although more ion exchange occurred on the molecular sieve, it was unquestionable that more chlorine stayed on the molecular sieve.When the copper loading amount was 10.00 mmol Cu 2+ /gHF, the mole ratio of Cu/Cl recovered a little.This may be because more Cu was generated, and Figure 4b veri ed this conjecture.

XPS analysis
In order to investigate the relationship between the valence states of the copper and the CO adsorption performance of the prepared adsorbents, XPS experiment was carried out.Figure 5a-d showed the survey XPS results of the prepared adsorbents.From Figure 5, Si, Al, Cu, Cl, C and O were all existed in the adsorbents.After activation at 170 ℃, 290 ℃ and 380 ℃, there was Si, Al, Cu, C and O still existed in survey spectra, while the characteristic peak of Cl gradually weakened and disappeared.From Figure 5, it was found that copper often existed in multiple forms simultaneously, and chlorine may be removed from the molecular sieve because of ion exchange.
Figure 6 showed the XPS spectra of Cu element in the adsorbents prepared at different conditions.Before activation, the adsorbent showed two intense peaks at 935.6 eV and 954.7 eV, accompanied with the Cu 2+ satellite peak at 940-947 eV, which could be attributed to the binding energy of Cu 2+ 2p3/2 and Cu 2+ 2p1/2 respectively, as shown in Figure 6a. Figure 6a also showed two intense peaks at 932.6 eV and 952.5 eV, which could be attributed to the binding energy of Cu + 2p3/2 and Cu + 2p1/2 respectively.The result was not in agreement with Gao's, and it indicated that there was Cu + coming into being in solvothermal process 19,40,41 .After activation at 170 ℃, 290 ℃ and 380 ℃, Cu 2+ 2p3/2 peak, Cu 2+ 2p1/2 peak, Cu + 2p3/2 peak and Cu + 2p1/2 peak still existed while the height of the peaks changed, which indicated the amount of Cu 2+ andCu + changed.The tted XPS spectra of the adsorbents activated at different temperatures was listed in Figure 7. From Figure 7 it was found that the amount of Cu + was the highest after activation at 290 ℃ while the amount of Cu + was the lowest before activation.Combining XRD and XRF analysis, it should be emphasized that Cu + existed not only as CuCl, but more as Cu(І)Y.
The XPS result showed a positive correlation with the CO adsorption performance of the adsorbent, which was in agreement with the above mechanism.

TG-MS analysis
TG-MS experiment was conducted to the mechanism of the adsorbent prepared at different stages, as shown in Figure 8.The experiment was carried out from room temperature to 290 ℃ at a rate of 5 ℃/min and then maintained for 1 h under Ar and the ow rate is 50 mL/min.From Figure 8a, the rst step weight loss was at about 50-110℃, which was attributed to the evaporation of water.The second weight loss step was at 150-290℃, which was attributed to the activation of the adsorbent.In the activation process, some Cu(CH 3 COO) 2 and CuCl 2 was reduced to CuCl, and a small amount of gases such as H 2 O and CO were generated correspondingly, as listed in Figure 8b.In activation process, as listed in Figure 8b too 41,42 , some CuCl exchanged with HY molecular sieve, and a small amount of gas such as HCl were generated correspondingly, as proposed in (3).
It was a pity that the mechanism was still not completely clear and further exploration were required.The question were below: 1.The role of C 2 H 5 OH in adsorbent preparing; 2. The transform of Cu(CH 3 COO) 2 ; How to enhance the ion exchange in the activation process

Figure
Figure 4b illustrated the XRD patterns of HY molecular sieve and the adsorbents prepared with different amounts of copper salt.When the copper loading was 3.5 mmol Cu 2+ /gHY, after activation at 290 ℃, only a little of Cu displayed a very weak diffraction peak at 43.3 o .When the copper loading was 7.0 mmol Cu 2+ /gHY, the diffraction peaks of Cu increased at 2θ values of 43.3 o and 50.4 o ; At the same time, the diffraction peaks of CuCl appeared.When the copper loading was 10.5 mmol Cu 2+ /gHY, not only the diffraction peaks of Cu and CuCl further increased, but also the diffraction peak of CuCl 2 appeared,

Figures
Figures

Figure 5 Survey
Figure 5

Table 1 .
2.1 Materials and preparations CuCl 2 •2H 2 O was obtained from Tianjin Fengchuan Chemical Co., Ltd., Cu (CH 3 COO) 2 •H 2 O and C 2 H 5 OH were purchased from Tianjin Hongyan Chemical Co., Ltd., and they were all AR grade without further puri cation.HY molecular sieve SiO 2 /A1 2 O 3 = 5.4 was purchased from Tianjin Nankai Catalyst Factory, which was pretreated before use.CO and Ar( 99.999 % ) were obtained from Henan Yuanzheng Special Gas Ltd., N 2 ( 99.999 % ) was purchased from Henan Yuanzheng Keji Co. Ltd., as listed in Cu(I)/Y were prepared from binary Cu(II) precursors using different dispersing agents.Firstly, different mole ratio of Cu (CH 3 COO) 2 •H 2 O/CuCl 2 •2H 2 .35 mL/g.When Cu(CH 3 COO) 2 •H 2 O/CuCl 2 •2H 2 O mole ratio was 1/1, the CO adsorption capacity of the prepared adsorbent increased signi cantly, which was similar to that of the adsorbent prepared with water as the solvent.When Cu(CH 3 COO) 2 •H 2 O/CuCl 2 •2H 2 O mole ratio was 3/1, the CO adsorption capacity of the prepared adsorbent reached a maximum, which was 12.67 mL/g.It was strange that the optimal Cu (CH 3 COO) 2 •H 2 O / CuCl 2 •2H 2 O mole ratio was no longer 1/1, but 3/1.The While using C 2 H 5 OH as the solvent, the experiment results were different.WhenCu(CH 3 COO) 2 •H 2 O/CuCl 2 •2H 2 Omole ratio was 1/3, the CO adsorption capacity of the prepared adsorbent was only 1 2 •H 2 O and CuCl 2 •2H 2 O loading on HY molecular sieve through solvothermal process, XRD did not show any information about Cu (CH 3 COO) 2 •H 2 O, CuCl 2 •2H 2 O or CuCl.The result was different from Xue

Table 3
listed the main chemical elements in the prepared adsorbents, and the mole ratio of Cu (CH 3 COO) 2 •H 2 O/CuCl 2 •2H 2 O was 3. It was found that the main elements in the adsorbents were Si, Al, Cu, Cl and Na elements.With the increase of copper loading from 1.75 mmol Cu 2+ /gHF to 10.5 mmol

Table 1 .
CAS registry number, purity and analysis method of the chemicals

Table 2
Physical adsorption parameters of adsorbent at different activation temperatures

Table 3
Main chemical elements in the prepared adsorbents