CN106676564B

CN106676564B - A kind of method and system of Direct Electrolysis biomass hydrogen preparation

Info

Publication number: CN106676564B
Application number: CN201710034775.4A
Authority: CN
Inventors: 邓渝林; 刘伟; 杜旭; 张喆; 刘聪敏
Original assignee: Individual
Current assignee: Individual
Priority date: 2017-01-18
Filing date: 2017-01-18
Publication date: 2019-04-23
Anticipated expiration: 2037-01-18
Also published as: CN106676564A

Abstract

The present invention is related to a kind of method and system of Direct Electrolysis biomass hydrogen preparation.Utilize the oxidation-reduction pair with redox function, as catalyst, its major function, which is embodied in oxidized form substance in oxidation-reduction pair, has oxidisability, can be using oxidizing biomass, the reduced form substance being reduced as charge carrier, by entrained electron transmission to anode tap；Electricity should have Hydrogen Proton generation in the process to biomass reverse, these are diffused into anode-side by the Hydrogen Proton separated in biomass, under the action of extra electric field, by proton exchange membrane, obtain electronics in cathode side and hydrogen is precipitated.Compared with prior art, the electrolytic method based on biomass does not need to add any noble metal catalyst on anode, and liberation of hydrogen is high-efficient.

Description

A kind of method and system of Direct Electrolysis biomass hydrogen preparation

Technical field

The present invention relates to a kind of method and system of Direct Electrolysis biomass hydrogen preparation, more particularly to are with oxidation-reduction pair The Direct Electrolysis biomass hydrogen preparation method and system of catalyst and electron transit mediator, belong to electrolysis biological matter hydrogen preparation field.

Background technique

Since increase and environmental crisis, renewable energy become the hot spot studied now year by year for global energy consumption.In crowd In multi fuel, Hydrogen Energy is considered as most clean fuel, because the combustion product of hydrogen is only water, does not include any pollution Object, such as CO₂Deng.In addition, Hydrogen Energy is a kind of efficient fuel, mass energy density is much higher than known to other any one Fuel type.The mass energy density of hydrogen is 33.3kWh/kg, that is to say, that the combustion of hydrogen of 1kg gives off energy about It is equivalent to the energy (11.1kWh/kg) of 3kg gasoline combustion release.

Although protium is the most abundant element of content in universe, there is no find hydrogen with simple substance in nature State exists.In recent years, hydrogen is also mainly prepared in a manner of gas renormalizing, coal gasification and water electrolysis.So And the mode that fossil fuel prepares hydrogen is not reproducible, while its by-product is for environment nocuousness.Further, since compared with High cathodic overvoltage exists, even if being used as catalyst, active oxygen evolution reaction using platinum (Pt) in proton membrane fuel battery Catalyst, the overvoltage of typical oxygen evolution reaction are about 300-400mV, so as to cause in water electrolysis process energy consumption it is high, because It is not a kind of ideal mode that this water electrolysis, which prepares hydrogen,.

Other than the mode of three of the above preparation of industrialization hydrogen, biofermentation and photodissociation hydrogen manufacturing (PEC) are very potential Hydrogen production process.However fermentation and photodissociation method all have that low efficiency and production hydrogen are unstable, therefore two kinds of hydrogen manufacturing modes are very Hardly possible realizes industrialization.Microorganism electrolytic hydrogen production technology is produced using microbial degradation organic substrates (alcohol or organic acid etc.) process Raw Hydrogen Proton, Hydrogen Proton obtain electronics generation hydrogen after penetrating proton exchange membrane, and microbiological fuel cell is a kind of effective system Hydrogen mode.But since the defects of microbiological life is limited, cell operating conditions are harsh, fermentation rate is slow, limits micro- life The efficiency and cost of object electrolysis biological matter hydrogen manufacturing.Proton exchange membrane electrolysis method is another common electrolytic hydrogen production technology, The faradic efficiency of hydrogen manufacturing is greatly improved using the noble metal of nanoscale as anode catalyst；However, the expensive gold of anode High metal catalyst cost is to restrict one of the development of proton exchange membrane electrolyzing pure water technology and heavy industrialization factor.Matter Proton exchange electrolytic hydrogen production can not directly utilize protist matter polymer, therefore noble metal catalyst can not urge at low temperature Change oxidation macromolecular biomass polymerization.Therefore, novel environmental-friendly, lasting, the inexpensive hydrogen manufacturing mode of one kind is found to compel in eyebrow Eyelash.

Summary of the invention

It to solve the above-mentioned problems, can be big the invention proposes a kind of method and system of Direct Electrolysis biomass hydrogen preparation Width improves electrolytic hydrogen production efficiency.

One aspect of the present invention provides a kind of method of Direct Electrolysis biomass hydrogen preparation, wherein uses oxidation-reduction pair As the catalyst and electron transit mediator in electrolysis biological matter hydrogen production process.

Another aspect of the present invention provides a kind of system of Direct Electrolysis biomass hydrogen preparation, wherein including electrolytic cell and electricity Pole, electrolytic cell are divided into anode electrolysis pond and catholyte pond by proton exchange membrane；First containing biomass and oxidized form substance is mixed After closing the preheated reaction of liquid, the second mixed liquor containing oxidation-reduction pair is obtained, as anolyte.

A kind of application of oxidation-reduction pair, wherein using the oxidation-reduction pair as catalyst and electron transit mediator, For Direct Electrolysis biomass hydrogen preparation.

Detailed description of the invention

Fig. 1 is a kind of electrolytic cell schematic diagram of embodiment；

Fig. 2 (a) is glucose and various concentration Fe³⁺After solution is mixed and preheated, electrolytic experiment polarization obtained is carried out Curve；

Fig. 2 (b) is Fe³⁺After mixing and preheat with the glucose of various concentration, it is bent to carry out electrolytic experiment polarization obtained Line；

Fig. 2 (c) is to carry out electrolytic experiment polarization curve obtained with glucose, potato starch and cellulose；

Fig. 3 (a) is glucose-iron ion electrolytic hydrogen production system under different constant electrolytic current densities, applied voltage Change with time trend；

Fig. 3 (b) is potato starch-iron ion electrolytic hydrogen production system under different constant electrolytic current densities, additional Voltage changes with time trend；

Fig. 3 (c) is cellulose-iron ion electrolytic hydrogen production system under different constant electrolytic current densities, applied voltage Change with time trend；

Fig. 3 (d) is glucose-iron ion hydrogen generating system under different constant electrolytic current densities, collected by cathode side Hydrogen volume change over time trend, and the hydrogen volume calculated according to Faraday's law；

Fig. 3 (e) is starch-iron ion hydrogen generating system under different constant electrolytic current densities, collected by cathode side Hydrogen volume changes over time trend；

Fig. 3 (f) is cellulose-iron ion hydrogen generating system under different constant electrolytic current densities, collected by cathode side Hydrogen volume change over time trend；

Fig. 4 be glucose-ferric ion solutions after 4 h of heating, after 10 electrolysis cycles¹H NMR spectra；

Fig. 5 (a) is that different lignin react the concentration versus time curve for generating ferrous ion with iron ion；

Fig. 5 (b) is Fe³⁺After mixing and preheat from different lignin, and not plus Fe³⁺Contrast groups, carry out electrolytic experiment, Polarization curve obtained；

Fig. 5 (c) is Fe³⁺After mixing and preheat with KL lignin, under the differential responses time, it is obtained to carry out electrolytic experiment Polarization curve；

Fig. 5 (d) is Fe³⁺After mixing and preheat with various concentration KL lignin, it is bent to carry out electrolytic experiment polarization obtained Line；

Fig. 5 (e) is when Faradaic current is 100mA/cm²When, liberation of hydrogen decomposition voltage change with time process (effectively electrolysis Area is 1cm²)；

Fig. 6 is three times after oxidization electrolysis circulation, lignin solid, liquid, carbon content in gas ratio；

Fig. 7 is KL lignin and FeCl₃After cell reaction, product liquid is analyzed using GC-Mass.

Specific embodiment

The present invention is explained in detail below in conjunction with specific embodiment.

A kind of method of Direct Electrolysis biomass hydrogen preparation, wherein using oxidation-reduction pair as electrolysis biological matter hydrogen manufacturing Catalyst and electron transit mediator in the process.

In a preferred embodiment, the oxidation-reduction pair can be Fe³⁺/Fe²⁺, Ag⁺/ Ag, Mn⁴⁺/Mn²⁺, TEMPO⁺/ TEMPO (tetramethyl piperidine oxides), AQ⁺One of/AQ (anthraquinone)；Particularly preferred Fe³⁺/Fe²⁺.But art technology Personnel are it is understood that the object that other electric right and present invention with oxidation-reduction quality are contemplated that；Especially work as oxidation Restore electric centering oxidized form substance can relatively easily biomass degradation, and when generating reduced form substance.

In a preferred embodiment, the optional inorganic elements oxidation-reduction pair of the oxidation-reduction pair, further It is preferred that transition metal element oxidation-reduction pair, such as Fe³⁺/Fe²⁺、Mn⁴⁺/Mn²⁺。

In a preferred embodiment, the electrolysis biological matter hydrogen production process carries out in proton exchange membrane electrolysis cells, electricity Solve the chemical equation during biomass hydrogen preparation are as follows:

In anode reaction pond:

Biomass+H₂O+ oxidized form substance → biomass portion oxidation product+reduced form substance+CO₂+H⁺ (1)

In anode-side:

Reduced form substance-e^-→ oxidized form substance (2)

In cathode side:

Net chemical reaction are as follows:

Biomass+H₂O → biomass oxidation product+CO₂+H₂ (4)

For example, when the oxidation-reduction pair selected is Fe³⁺/Fe²⁺When, the chemical reaction in electrolysis biological matter hydrogen production process Equation are as follows:

Biomass+H₂O+Fe³⁺→ biomass portion oxidation product+Fe²⁺+CO₂+H⁺ (1’)

In anode-side:

Fe²⁺-e^-→Fe³⁺ (2’)

In cathode side:

Net chemical reaction are as follows:

Biomass+H₂O → biomass oxidation product+CO₂+H₂ (4’)

From the above reaction equation: the main function of oxidation-reduction pair is in entire electrolytic process: (1) oxidized form Substance, i.e. high-valence state component, such as Fe³⁺、Ag⁺、Mn⁴⁺、TEMPO⁺、AQ⁺, as oxidant biomass degradation macromolecular；Reduced form Substance, i.e. lower valency component, Fe such as corresponding with oxidized form substance²⁺、Ag、Mn²⁺, TEMPO, AQ, as charge carrier by electronics It is transferred to anode electrolytic cell.(2) oxidation-reduction pair is mutually converted in electrolytic process, is completely renewable, therefore in fact The effect played on border is electrochemical catalyst.

As shown in formula (2), (2 '), under the action of an external electric field, reduced form substance is oxidized to oxidation again on anode Type substance；The H generated in anode reaction pond⁺Enter cathode side through proton exchange membrane, is reduced to H in cathode side₂, such as formula (3), shown in (3 ').

In a preferred embodiment, in anode reaction pond, i.e., in formula (1), to containing biomass and oxidized form substance The first mixed liquor (formula on the left of) preheated, after pre- thermal response, obtain the second mixed liquor (right side of the formula)；Described second is mixed It closes in liquid and contains oxidation-reduction pair, wherein the molar ratio of oxidized form substance and reduced form substance is 1:10-10:1, preferably 1:4- 4:1.When being electrolysed under the molar ratio, since oxidized form substance in oxidation-reduction pair and reduced form material proportion are suitable In, circuit runs smoothly, and tests liberation of hydrogen effect achieved also more preferably.It is understood that those skilled in the art can basis Actual needs carries out value within the above range, such as to each group oxidation-reduction pair, chooses oxidized form substance and reduced form object The molar ratio of matter be 1:10,1:9,1:8,1:7,1:6,1:5,1:4,1:3,1:2,1:1,2:1,3:1,4:1,5:1,6:1,7:1, 8:1,9:1,10:1 etc..

The oxidized form substance in aqueous solution aoxidizes biomass under the conditions of heating or illumination etc., and oxidized form substance Itself is reduced to compared with lower valency.The reduced form material transport of lower valency is oxidized under the action of electrolytic anode to electrolytic anode Regeneration.Hydrogen is generated under the action of electrolysis cathode simultaneously.Total reaction is in anode during Direct Electrolysis biomass hydrogen preparation Side biomass is oxidized and in cathode side generation hydrogen.

In a preferred embodiment, in anode reaction pond, i.e., in formula (1), to containing biomass and oxidized form substance The first mixed liquor preheated, when oxidized form substance be inorganic elements when, preheating temperature is preferably 25-250 DEG C, particularly preferably It is 25-150 DEG C, such as works as and select oxidized form substance for Fe³⁺、Ag⁺、Mn⁴⁺When；When oxidized form substance is organic element, preheating temperature Preferably 25-150 DEG C of degree, especially preferably 25-120 DEG C, such as works as and select oxidized form substance for TEMPO⁺、AQ⁺When.Preheated Cheng Zhong, part biological matter macromolecular oxidative degradation can be become small-molecule substance by oxidized form substance, and oxidized form substance is reduced For reduced form substance, after preheating, oxidized form substance and reduced form substance, such as Fe are existed simultaneously in the second mixed liquor³⁺/Fe² ⁺, Ag⁺/ Ag, Mn⁴⁺/Mn²⁺, TEMPO⁺/ TEMPO (tetramethyl piperidine oxides), AQ⁺/ AQ (anthraquinone)；The preheating temperature for The degradation of biomass has large effect, and it is very crucial for selecting suitable preheating temperature, it is to be understood that this field skill Art personnel can carry out value according to actual needs within the above range, such as to the former, preheating temperature can be 25 DEG C, 30 ℃、40℃、50℃、60℃、70℃、80℃、90℃、100℃、110℃、120℃、130℃、140℃、150℃、 160℃、 170 DEG C, 180 DEG C, 190 DEG C, 200 DEG C, 210 DEG C, 220 DEG C, 230 DEG C, 240 DEG C, 250 DEG C etc.；To the latter, preheating temperature can be with For 25 DEG C, 30 DEG C, 40 DEG C, 50 DEG C, 60 DEG C, 70 DEG C, 80 DEG C, 90 DEG C, 100 DEG C, 110 DEG C, 120 DEG C, 130 DEG C, 140 DEG C, 150 DEG C etc..

It is worth noting that, the anode reaction pond can refer to anode electrolysis pond, also can refer to as the first mixed liquor preheating and anti- The reaction tank answered and be separately provided.In other words, the first mixed liquor may be selected first in anode electrolysis pond (anode reaction pond) into Then the pre- thermal response of row directly applies applied voltage and carries out electrolysis biological matter hydrogen production process；Alternatively, the first mixed liquor can also be first Pre- thermal response is carried out in reaction tank, is then then transferred to anode electrolysis pond, is applied applied voltage and is carried out the hydrogen manufacturing of electrolysis biological matter.

In addition, in first mixed liquor, mainly biomass, oxidized form substance and water, before preheating, due to certain property The biomass of matter wave living, such as glucose can slowly be reacted with the generation of oxidized form substance, and generate micro reduced form object Therefore matter can contain micro oxidation-reduction pair in the first mixed liquor；But the main oxidation-reduction pair of the present invention is to deposit It is in the second mixed liquor.

In a preferred embodiment, in the electrolytic process, the temperature of anolyte and catholyte is controlled At 50-100 DEG C.The temperature range is more advantageous to electrolysis and carries out, it is to be understood that those skilled in the art can be according to reality Border needs, and carries out value within the above range, such as can be 50 DEG C, 60 DEG C, 70 DEG C, 80 DEG C, 90 DEG C, 100 DEG C etc..

In a preferred embodiment, oxidized form substance can be ionic compound or oxide, and reduced form substance can be Ionic compound, organic compound or simple substance.In first mixed liquor, such as Fe³⁺Optional FeCl₃Aqueous solution, Fe₂(SO₄)₃ Aqueous solution, Fe (NO₃)₃One of ferric salt solutions such as aqueous solution after preheating, contain Fe in obtained the second mixed liquor³⁺/ Fe²⁺Electricity is right；Such as Ag⁺Optional AgNO₃Aqueous solution after preheating, contains Ag in obtained the second mixed liquor⁺/ Ag electricity is right, and wherein Ag is Simple substance；Such as Mn⁴⁺Optional MnO₂, after preheating, contain Mn in obtained the second mixed liquor⁴⁺/Mn²⁺Electricity is right；Such as TEMPO⁺Optional TEMPO⁺Deionized water solution after preheating, contains TEMPO in obtained the second mixed liquor⁺/ TEMPO electricity is right；Such as AQ⁺Optional AQ⁺Aqueous solution, After preheating, contain AQ in obtained the second mixed liquor⁺/ AQ electricity is right, and wherein AQ is anthraquinone compounds；But it is understood that Easily reacting with biomass after the heating of oxidized form substance and generating reduced form substance is criterion, therefore is not limited to above-mentioned optional Solution.

In a preferred embodiment, concentration of the oxidized form substance in the first mixed liquor is chosen as 0.1-5mol/L, example Such as 0.1 mol/L, 0.5mol/L, 1mol/L, 2mol/L, 3mol/L, 4mol/L, 5mol/L；Such as Fe³⁺In the first mixing Concentration in liquid is chosen as 0.1-3mol/L, and 0.1mol/L, 0.5mol/L, 1mol/L, 2mol/L, 3mol/L specifically may be selected Etc..

In a preferred embodiment, in first mixed liquor, glucose, potato starch, wood is may be selected in biomass One of quality, cellulose, hemicellulose, stalk, vinasse, algae, seaweed, sludge organic matter etc. are a variety of.Biomass It can be biomass soluble easily in water, the biomass of water can also be soluble or insoluble in for hardly possible.

When biomass is soluble biomass, such as glucose, potato starch, preferably it is in the first mixed liquor Concentration is 0.1-4mol/L, such as 0.5mol/L, 1mol/L, 2mol/L.When biomass is insoluble or less soluble biomass, Such as lignin, preferably its concentration in the first mixed liquor are 1-30g/L, such as 5g/L, 10g/L, 15g/L, 20g/L, 25g/L Deng.

In a preferred embodiment, in catholyte pond, H may be selected₃PO₄The conventional electrolysis liquid such as aqueous solution is as yin Pole electrolyte, it is 0.1-3mol/L that its concentration, which may be selected,；The application is primarily upon anolyte, therefore not to catholyte Liquid does excessive limitation, other conventional cathodes electrolyte, if aqueous sulfuric acid, phosphoric acid solution are that can use.Anode electrolysis The molar ratio of liquid and catholyte is preferably 1:1-1:2, such as 1:1,1:2；In conventional experiment, 1:1 ratio is selected.

Due to oxidation-reduction pair and/or biomass in the present invention, it is possible to for it is soluble easily in water, be insoluble in water or insoluble Yu Shui, therefore the mixing of the two is stated using mixed liquor (such as the first mixed liquor, the second mixed liquor), rather than the shape of mixed solution Formula statement；As it can be seen that including the concept of mixed solution in mixed liquor.

A kind of system of Direct Electrolysis biomass hydrogen preparation, wherein including electrolytic cell and electrode, electrolytic cell is by proton exchange membrane It is divided into anode electrolysis pond and catholyte pond；After the preheated reaction of the first mixed liquor containing biomass and oxidized form substance, obtain The second mixed liquor containing oxidation-reduction pair, as anolyte.At this point, both containing oxidized form object in the second mixed liquor Matter also contains reduced form substance.It is raw that the Direct Electrolysis can be used in the method for previously described Direct Electrolysis biomass hydrogen preparation The system of substance hydrogen manufacturing is achieved.

In a preferred embodiment, the oxidized form substance can be Fe³⁺、Ag⁺、Mn⁴⁺、TEMPO⁺、AQ⁺One of, Obtained oxidation-reduction pair is respectively Fe³⁺/Fe²⁺, Ag⁺/ Ag, Mn⁴⁺/Mn²⁺, TEMPO⁺/ TEMPO, AQ⁺/AQ；Particularly preferred oxygen Change type substance is Fe³⁺.It will be appreciated by persons skilled in the art that other, which have, to aoxidize biomass, and valence state itself drops The low oxidized form substance with oxidisability or strong oxidizing property is also the object that the present invention is contemplated that.

As an implementation, the electrolytic cell and electrode can be conventional electrolytic cell equipment, and proton exchange membrane will be electric Solution slot is divided into anode electrolysis pond and catholyte pond, and anode plate is located at anode electrolysis pond, and cathode plate is located at catholyte pond.It is described Anode plate and cathode plate are using conventional material preparation, for example, graphite electrode or anode plate can be used using graphite Electrode, cathode plate is using metal electrode, etc..

As another embodiment, the electrolytic cell is divided into anode electrolysis pond and catholyte pond, anode electrolysis pond with Anode plate is connected, and catholyte pond is connected with cathode plate；Electrolyte channel is respectively set in anode plate and cathode plate, anode plate and Proton exchange membrane is set between cathode plate.The first peristaltic pump can be used, the second mixed liquor in anode electrolysis pond is pumped into anode plate In, the electrolyte in catholyte pond is pumped into cathode plate using the second peristaltic pump；Electrolytic cell two sides under the action of peristaltic pump, It is respectively formed anolyte circulation and catholyte circulation.In this way, under the action of an external electric field, reduced form substance is in anode plate On be oxidized to oxidized form substance again, and return to anode electrolysis pond；The H generated on anode plate⁺It is directed through proton exchange membrane Into cathode side, H is reduced on cathode plate₂。

In a preferred embodiment, anode plate can have one or more runners, and graphite felt can be embedded in anode stone To increase electrolysis effectiveness in the runner of electrode ink；Cathode plate may include multi-layer gas diffusion admittance, in order to be precipitated on cathode plate Hydrogen quickly spread.

In a preferred embodiment, H can be selected in the catholyte pond of the electrolytic cell₃PO₄Aqueous solution as electrolyte, It is preferred that its concentration is 0.5-3mol/L.

In a preferred embodiment, the cathode side supported catalyst of proton exchange membrane, the catalyst can be noble metal Catalyst, such as platinum, rhodium, palladium, preferably its load capacity are 0.2-1mg/cm²；Also may be selected non-precious metal catalyst, as nickel, chromium, Titanium etc., preferably its load capacity are 1-10mg/cm²；It is also an option that non-metallic catalyst, such as nitrogen-doped carbon, sulfur doping carbon, it is excellent Selecting its load capacity is 1-10mg/cm²；Or the mixing of the arbitrary proportion for above-mentioned three kinds of catalyst, preferably its load capacity are 0.1-10mg/cm².For the present invention, particularly preferred load capacity is 0.2-1mg_Pt/cm²Platinum carbon.The catalyst is urged as liberation of hydrogen Agent can accelerate liberation of hydrogen speed, improve hydrogen generation efficiency.

The setting of conditional parameter involved in the application process of above-mentioned oxidation-reduction pair, with Direct Electrolysis described previously Parameter in biomass hydrogen preparation method and system is identical with hardware configuration.

Compared with prior art, the invention has the benefit that

(1) it the present invention provides a novel low cost, low energy consumption method and system, is electrolysed using proton exchange membrane Pond, liquid catalyst Direct Electrolysis high polymerization degree biomass produce hydrogen.By described method and system, biomass can be It is aoxidized with type substance is directly oxidized in the mixed liquor of water, so that anode-side no longer needs any other noble metal catalyst.

(2) hydrogen manufacturing of oxidation-reduction pair catalytic electrolysis, oxidation-reduction pair are used in entire electrolysis biological matter hydrogen production process Catalyst plays an extremely important role；By taking iron ion as an example, in anode reaction side, iron ion on the one hand be used as oxidant with Biomass reverse is answered, and electronics is captured during biomass degradation, and the electronic delivery of carrying is discharged into external circuit to anode-side In.At the same time, iron ion and biomass reverse should during have Hydrogen Proton generation, these are by the Hydrogen Proton that separates in biomass It is diffused into anode-side, under the action of extra electric field, by proton exchange membrane, electronics is obtained in cathode side and hydrogen is precipitated.

(3) novel redox electricity involved in the present invention is to catalytic electrolysis biomass hydrogen preparation process for the first time using oxidation Reduction electricity directly utilizes high polymerization degree biomass work to substituting traditional anode noble metal solid catalyst as catalyst For electrolytic hydrogen production raw material rather than traditional electrolyte water process for making hydrogen, have that hydrogen generation efficiency is high, low energy consumption, environmental-friendly etc. excellent Gesture.

Full and accurate narration is carried out to the present invention below in conjunction with drawings and examples, it is notable that the implementation Example is only that preferred embodiments of the present invention will be described, is not intended to limit the scope of the present invention, this is not being departed from Under the premise of invention design spirit, various modifications and change that those of ordinary skill in the art make technical solution of the present invention Into, should all fall into claims of the present invention determine protection scope in.

FeCl is used in the present invention₃Representative of the aqueous solution as oxidized form substance, especially as ferric salt solution Representative is illustrated, the property of other oxidized form substances and effect and FeCl₃It is close similar or identical；Biomass mainly selects ratio More representational glucose, potato starch, cellulose, lignin etc. are illustrated for representative.

The electrolytic cell referred in second of embodiment of the system of Direct Electrolysis biomass hydrogen preparation is considered simultaneously, due to The effect of peristaltic pump is more advantageous to the electrolysis of biomass so that the distribution of electrolyte is more advantageous, thus following embodiment with Graphite electrode containing peristaltic pump and containing runner carries out analysis and understanding as the representative of electrolytic cell；It should be understood that described first The electrolytic cell that kind embodiment provides also is able to achieve identical function, and the present invention repeats no more.

Embodiment 1: glucose/potato starch/cellulose-iron ion Direct Electrolysis hydrogen generating system

1. Fe under high temperature³⁺/Fe²⁺The redox reaction of oxidation-reduction pair and biomass

(1) mixed solution (i.e. the first mixed liquor) is prepared:

Biomass is added to FeCl by taking glucose as an example, by a certain amount of glucose₃In aqueous solution, electromagnetic agitation can be used Mode make glucose acceleration be dissolved in FeCl₃In solution, mixed solution is obtained；The parameter of each solute in obtained mixed solution As shown in table 1, while one group of control group 1 is set, solute parameter is equally shown in Table 1:

Table 1: each group experiment parameter

(2) mixed solution is preheated:

To experimental group 1-4,50ml mixed solution is taken to be transferred in glass spinner flask respectively, heats 4h under the conditions of 90 DEG C, It can whole electromagnetic agitation.When heating after a certain period of time, it is possible to find the mixed solution of yellow gradually becomes rufous, and supplement is gone in right amount It is 50ml that ionized water, which maintains liquor capacity, at this point, both containing Fe in the solution of rufous²⁺Ion, and contain Fe³⁺, referred herein to its For biomass-ferric ion solutions (i.e. the second mixed liquor).

To experimental group 5-9,80ml mixed solution is taken to be transferred in glass spinner flask respectively, heats 4h under the conditions of 100 DEG C, It can whole electromagnetic agitation.When heating after a certain period of time, it is possible to find the mixed solution of yellow gradually becomes rufous, and supplement is gone in right amount It is 80ml that ionized water, which maintains liquor capacity, at this point, the solution of rufous is both to contain Fe²⁺Ion, and contain Fe³⁺Biomass- Ferric ion solutions.

(3)Fe³⁺Reducing degree detection

A small amount of biomass-ferric ion solutions are taken to dilute 50,000 times as sample, for analyzing Fe³⁺Reducing degree. Due to Fe²⁺Solution can be transformed into the iron ion complex compound for having extremely strong absorbance in 510nm with the reaction of 1,10- phenanthroline, Fe can be determined by spectrophotometry²⁺Concentration, and then analyze Fe³⁺Reducing degree.

In the present embodiment in the selected finally obtained biomass-ferric ion solutions of experimental group (the second mixed liquor), subsequent warp Cross measurement, Fe³⁺And Fe²⁺Molar ratio in the ratio range of 1:4-4:1.

2. electrolysis biological matter hydrogen manufacturing

(1) electrolytic cell is arranged

Biomass electrolytic experiment a laboratory scale, can to carry out in the proton exchange membrane electrolytic cell of continuous operation, As shown in Fig. 1, electrolytic cell is divided into anode electrolysis pond and catholyte pond, and anode electrolysis pond is connected with anode plate, catholyte pond It is connected with cathode plate, anode plate and cathode plate are all made of graphite electrode plate.The a piece of Nafion115 model matter by having pre-processed Proton exchange is between two panels graphite electrode plate；Anode plate has multiple runners, and graphite felt is embedded in the runner of anode plate.Yin Pole is the electrode comprising five layers of gas diffusion paths, and cathode is used uniformly the H that concentration is 1mol/L₃PO₄Solution is as cathode Electrolyte.

(2) electrolysis biological matter hydrogen production process

Take respectively prepared biomass-ferric ion solutions be placed in anode electrolysis pond, be by concentration at the same time The H of 1mol/L₃PO₄Aqueous solution is placed in catholyte pond, and two sides under the action of each peristaltic pump, are respectively formed anodic dissolution Circulation and cathode solution circulation.After both ends liquid circulation is stablized, apply in the cathode of electrolytic cell and anode two sides certain outer Making alive can control the size of applied voltage, and size of current in measuring circuit, in cathode electricity by electrochemical workstation Xie Chizhong collects generated hydrogen.

When using glucose as raw material, because glucose is easily by Fe³⁺Oxidation, can be complete under relatively mild conditions Portion is oxidized to CO₂.Its net chemical equation are as follows:

C₆H₁₂O₆+6H₂O→6CO₂+12H₂ (5) 3. the electrology characteristic of biomass-ferric ion solutions electrolytic hydrogen production process measures

(1)Fe³⁺/Fe²⁺Influence of the oxidation-reduction pair to electrolytic hydrogen production

Select comparative experiments of the control group 1 as experimental group 1-4；Mixed solution in control group 1 is placed in anode electrolysis Electrolytic experiment is carried out in pond, control electrolyte temperature is 80-100 DEG C or so.When decomposition voltage increases to 1.2V (outer power-up at this time Pressure has been approached the ideal electroaffinity 1.23V of water) when, do not detect that apparent electric current occurs in circuit.

Biomass-ferric ion solutions that experimental group 1-4 is obtained select 50mL anolyte and catholyte respectively Liquid is operated according to the electrolysis biological matter hydrogen production process of (2) step in step 2, and maintenance electrolyte temperature is a 80-100 DEG C of left side The right side, shown in experimental result such as Fig. 2 (a), Fig. 2 (a) is 1mol/L glucose and different Fe³⁺After strength solution mixing, at 90 DEG C Under the conditions of heat 4 hours, then carry out electrolytic experiment polarization curve obtained.

In Fig. 2 (a), from experimental result it can be seen that when Fe is added³⁺After catalyst, apparent electricity can detecte Solve electric current.When the external voltage of application is less than 0.7V, electrolytic current density very little in external circuit, and when decomposition voltage about When 0.7V, electric current increases obviously, and and Fe³⁺Concentration has strong positive correlation, and at the same time, cathode side can be observed significantly To there is bubble generation.

It is above the result shows that, by biomass solution and Fe³⁺/Fe²⁺The mixed solution heating of oxidation-reduction pair can draw The redox reaction of substance, the degree and Fe of reaction occurs³⁺Concentration is related, under the more high identical decomposition voltage of the extent of reaction, Current density is bigger.The above comparative experiments also indicates that, H₂O, glucose and Cl^-Any noble metal catalyst cannot not loaded It is aoxidized on graphite electrode, but biomass and the Fe such as glucose, potato starch, cellulose after preheating³⁺/Fe²⁺Redox electricity To that can be electrolysed under lower applied voltage, hydrogen is generated.

Work as Fe³⁺When concentration is 1mol/L (experimental group 4), when additional decomposition voltage is 1.0V, current density is reachable 266mA.Even if under conditions of anode-side does not load any noble metal catalyst, lower the obtained current density of conditions above The current density of ethanol hydrogen production under the identical decomposition voltage reported higher than existing literature, such as Caravaca, A., et al., Electrochemical reforming of ethanol–water solutions for pure H2production in a PEM electrolysis cell. International Journal of Hydrogen Energy,2012.37 (12): being reported in p.9504-9513., current density is 200mA/cm under 1.0V decomposition voltage²。

In addition, with Fe³⁺The value of the raising of concentration, electrolysis starting point (Faradaic current suddenly increased point) gradually decreases, And the slope of polarization curve increases.Faradaic current increases show Fe suddenly²⁺Start in graphite anode plate by electroxidation.From another The slope value of a angle analysis, polarization curve is bigger, and current density obtained is stronger under same applied voltage, that is, Say that hydrogen is precipitated by proton exchange membrane in more Hydrogen Protons in same time.Therefore, under same decomposition voltage, for For the relatively other electrolysis systems of biomass-iron ion electrolytic hydrogen production system, bigger energy output, hydrogen output can be obtained It is higher.

(2) influence of the biomass concentration to electrolytic hydrogen production

The concentration of biomass is also to influence one of the influence factor of electrolytic hydrogen production efficiency, therefore the present embodiment also tested life Influence of the material concentration for the effect of electrolysis liberation of hydrogen；Biomass is using for representative glucose in the present embodiment.

When experiment, comparative experiments of the control group 2 as experimental group 5-9 is selected；Respectively selection 80mL anolyte and 100mL catholyte；It is operated according to the electrolytic hydrogen production process of (2) step in step 2, maintenance electrolyte temperature is 80- 100 DEG C or so, shown in experimental result such as Fig. 2 (b), Fig. 2 (b) is 1mol/L Fe³⁺It is mixed with the glucose solution of various concentration Afterwards, it is heated under the conditions of 100 DEG C 4 hours, then carries out electrolytic experiment polarization curve obtained.

In Fig. 2 (b), with the increase of concentration of glucose, under the conditions of identical outer plus decomposition voltage, electrolytic current density Increase therewith.If with the presence of more glucose molecules, glucose molecule and Fe in mixed solution³⁺Ion collides general Rate increases, so that the probability of initiated oxidation reduction reaction increases therewith, improves reaction rate.This experimental results showed that, it is right In biomass-iron ion electrolytic hydrogen production system, electrolytic current density is can be improved in higher glucose concentration.It compares simultaneously Experiment illustrates catalyst Fe again³⁺/Fe²⁺Importance of the oxidation-reduction pair to electrolytic hydrogen production.

In summary, it is seen that catalyst Fe³⁺/Fe²⁺Concentration with biomass glucose is hydrogen production process two critically important Influence factor.

(3) analysis of other biological matter electrolytic hydrogen production

Other than glucose, the present invention additionally uses other kinds of biomass, illustrates Fe³⁺/Fe²⁺Liquid catalyst electricity Solving biomass hydrogen preparation system has wide applicability.It is with potato starch and cellulose (both for soluble biomass) Example, as a comparison using glucose, has carried out electrolytic experiment if other conditions are the same.

When experiment, prepare respectively containing glucose, potato starch, cellulose 3 groups of mixed solutions, wherein every group of mixing is molten The concentration of biomass is 1mol/L in liquid, and Fe³⁺Concentration in mixed solution is also 1mol/L；It is molten for every group of mixing Liquid performs the following operation respectively: after heating 8 hours at 100 DEG C, then selecting 50mL anolyte and 100mL cathode Electrolyte carries out electrolytic experiment according to the electrolytic hydrogen production process of (2) step in step 2, maintains electrolyte temperature at 50 DEG C or so. After applying external voltage, it can detect that electric current exists in biomass-iron ion electrolysis system.Its experimental result such as Fig. 2 (c) shown in, Fig. 2 (c) is that electrolytic experiment polarization song obtained is carried out with glucose, potato starch and cellulose and iron ion Line.

In Fig. 2 (c), when applied voltage is 1.0V, the electrolytic current density of potato starch and cellulose is respectively 239 mA/cm²And 0.158A/cm².Starch-iron ion polarization curve and glucose-iron ion electrolysis polarization curve are very close, This is because starch and glucose chemical composition are close, it can be in 100 DEG C or so and Fe³⁺Reaction is oxidized.However, when biology Qualitative change be cellulose when, under same decomposition voltage, current density be significantly less than glucose-iron ion and starch-iron from Sub- electrolytic current density, this shows that the reaction rate of cellulose and iron ion is lower than glucose and Ma Ling under identical reaction condition The reaction rate of sweet potato starch and iron ion.There are many reason may cause experimental phenomena above generation, for example, with glucose and Potato starch is compared, and cellulose has rigid crystals structure；Solubility in biggish physical size, water is small.However, practical Fe in upper biomass-iron ion polarization curve slope and solution²⁺Concentration is directly related rather than the chemical property of biomass, this It is because the oxide material that actually occurs on anode is Fe²⁺, rather than biomass.Therefore, although the chemical property of biomass Biomass-iron ion reaction dynamics, but the current density and Fe of electrolytic cell can be directly affected²⁺Concentration is main correlation 's.

4. liberation of hydrogen rate

In order to assess biomass-iron ion electrolytic hydrogen production system, respectively 50,100,200mA/cm²Three constant current electricity The change curve of cell voltage is measured under conditions of solution.

When experiment, prepare respectively containing glucose, potato starch, cellulose 3 groups of mixed solutions, wherein every group of mixing is molten The concentration of biomass is 1mol/L in liquid, and Fe³⁺Concentration in mixed solution is also 1mol/L；It is molten for every group of mixing Liquid performs the following operation respectively: after heating 8 hours at 100 DEG C, glucose-ferric ion solutions for obtaining at this time, starch- In ferric ion solutions, cellulose-ferric ion solutions, Fe³⁺/Fe²⁺Ratio be respectively 10:1,10:1,10:1；Then to each group Solution selects 50mL anolyte and 50mL catholyte, carries out electricity according to the electrolytic hydrogen production process of (2) step in step 2 Solution experiment, maintains electrolyte temperature at 90-100 DEG C, including catholyte pond temperature, anode electrolysis pond temperature, in this way in anode Fe in electrolytic cell³⁺It can be with the combined material continuous generation oxidation reaction of biology；At the same time, cathode side has hydrogen generation, passes through drainage Carry out product collection.

When Fig. 3 (a) show biomass selection glucose, respectively with 50,100,200mA/cm²Three constant-current electrolysis Under the conditions of test voltage changing rule.When biological qualitative change is by potato starch, cellulose substitution glucose, voltage change is bent Line trend is identical, as shown in Fig. 3 (b) and 3 (c).Under the conditions of experimental setup, glucose-ferric ion solutions are available most Broad theory current density is 210.4mA/cm².Therefore, in order to keep stable liberation of hydrogen rate, electric current during constant-current electrolysis Density should compare 210.4mA/cm²It is slightly smaller, 50,100,200mA/cm are had chosen respectively in subsequent research²Three current densities Carry out electrolytic experiment.From Fig. 3 (a) as can be seen that when current density increases to 100,200mA/cm by 50²When, glucose-iron The decomposition voltage of ion electrolysis hydrogen generating system increases to 0.7V, 0.9V by 0.6V.When the constant electrolysis of electric current, battery applied voltage Always it maintains to stablize.Stable electrolysis liberation of hydrogen depends on stable applied voltage, and stable applied voltage depends on glucose Stable electronics transfer between iron ion, it means that suitable Fe³⁺/Fe²⁺Molar ratio, so that biomass-iron ion The reaction rate of solution is enough to provide Stable Proton and electronics for electrolytic process.

In this experiment, the volume by measuring precipitation hydrogen under different current densities can calculate the speed of electrolytic hydrogen production Rate, as shown in Fig. 3 (d).In with biomass-iron ion system composed by different material, under different experimental conditions, respectively Collect 24mL hydrogen, such as Fig. 3 (d), 3 (e) and 3 (f).Biomass-iron ion hydrogen manufacturing for different biomass material compositions For system, (50,100,200mA/cm under different constant electrolytic current densities²), the generating rate and electric current of hydrogen are close Degree is related, and unrelated with biomass material type.For example, when current density is 100mA/cm², glucose, potato starch and The liberation of hydrogen rate of cellulose is 0.0109,0.0108 and 0.0108ml/s respectively.

Result above also demonstrates that electrolytic process follows Faraday's law.Under different electrolytic current densities, the precipitation of hydrogen Rate such as table 2.Experimental data obtained by glucose-iron ion electrolytic hydrogen production system and analysis calculated under different current densities Hydrogen rate value compares, and experiment value is very close with calculated value, as shown in Fig. 3 (d).Whole experimental results have all reached very high Faradic efficiency: experimental result is slightly below calculated value, and for glucose-iron ion system, its average faradic efficiency is 90.63%.Efficiency loss may be since gas leakage is made in the impedance of glucose-ferric ion solutions and gas collection process At.

Table 2 is shown for glucose-iron ion system, is generated needed for 24ml hydrogen under different electrolytic current densities Decomposition voltage, electrolysis energy consumption and under this condition generate hydrogen theoretical value (25 DEG C, 1cm²Proton exchange membrane pure water electrolysis)

Table 2: glucose-iron ion hydrogen generating system is under different electrolytic current densities, liberation of hydrogen parameter

5. product analysis

Formula (5) refers to when glucose is completely by Fe³⁺Product after oxidation is CO₂, but in fact, glucose electrolytic process It is related to multiple reaction steps.It, can be by analyzing final reaction product and biomass in biomass-iron ion hydrogen generating system The amounts of hydrogen of middle release, to deduce specific redox reaction.However, final product is not to the utmost under different reaction conditions It is identical, such as reaction time, reaction temperature and iron concentration, biomass type.Although some complexity have occurred in systems Redox reaction, but under the experiment condition of setting find macromolecule biomass polymers can be oxidized to small point Son measures each analog derivative.By analysis means such as nuclear-magnetism, gas phase-mass spectrograph and total organic carbon analyzers for being present in anode electricity Organic substance in Xie Chi, being oxidized has carried out detailed chemical analysis, as shown in Figure 4.Although being related in our current research more The biomass material of seed type, such as potato starch, cellulose, glucose, in the redox of different kind organism matter-iron ion The final product of reaction has had been found that the small organic molecules such as formic acid, acetic acid.For gas-phase product, by the gaseous product of anode into It has gone and has collected and analyzed using chromatography of gases, CO₂It is unique gaseous product.With electrolysis time and extending heating time, first The content of acid and acetic acid gradually increases, this shows that degradation reaction has occurred in biomass material.(TOC) knot is analyzed according to total organic carbon Fruit, in glucose-iron ion electrolytic hydrogen production system after 10 heating-electrolysis cycles, about 43% organic carbon is converted For CO₂。

6. thermodynamic analysis

Based on above chemical analysis and electrochemical property test, we are also to using proton exchange membrane liquid catalyst biology The upright technology for connecing electrolysis biological matter hydrogen manufacturing has carried out thermodynamic analysis, and detailed process is as follows:

Firstly, Fe³⁺It is answered at a certain temperature with biomass reverse, biomass is partially oxidized, Fe³⁺It is reduced to Fe²⁺。 Under the action of extra electric field, the Fe of reduction-state²⁺Electronics is provided for the electrochemical oxidation process of anode.Charge is by Fe²⁺It is transferred to Anode-side, as shown in chemical equation (2), which is not required to expensive metal catalysis, therefore considerably reduces hydrogen manufacturing Cost.In addition, Fe²⁺Stable chemical property is all had with graphite electrode, is not easy to be poisoned by a small amount of impurity in fuel.

H released in biomass degradation process⁺Anode-side is diffused to, then passes through proton under the action of external electric field Exchange membrane obtains external circuit in cathode side and is electronically generated hydrogen.Therefore, with traditional proton exchange membrane electrolysis water or electrolysis first Alcohol, ethanol hydrogen production technology are compared, and liquid catalyst Direct Electrolysis biomass hydrogen preparation technology provided by the invention has low energy consumption, non-expensive The characteristics of metal catalytic.By taking glucose as an example, in electrolytic process at middle glucose as electronics and H⁺Donor can directly exist The small molecule organic matter of low polymerization degree is hydrolyzed under heating condition.Under the conditions of continuous heating, final catabolite be formic acid, Acetic acid and CO₂.When biomass replaces with potato starch and cellulose, played the role of, warp similar with glucose Certain reaction time is spent, final gas phase reaction product is also CO₂.By the analysis to liberation of hydrogen rate part it is found that for Portugal Grape sugar-iron ion system, energy consumption are directly related with additional decomposition voltage.When given current density is respectively 200mA/cm²With 100 mA/cm²When, the electric energy that can calculate consumption is respectively 1.936kWh/Nm³And 1.567kWh/Nm³.Here, by inhomogeneity The electrolysis biological matter hydrogen producing technology of type is compared, and the results are shown in Table 3.

The different biomass electrolytic hydrogen production Technical comparings of table 3

The data source of 2 Literature A of table is in (1) Bentivenga, G., et al., Degradation of steam- exploded lignin from beech by using Fenton's reagent.Biomass&Bioenergy, 2003.24(3):p.233-238.(2)Neyens, E.and J.Baeyens,A review of classic Fenton's peroxidation as an advanced oxidation technique. Journal of Hazardous Materials,2003.98(1-3):p.33-50.(3)Ragland,K.W.,D.J.Aerts,and A.J. Baker, Properties of Wood for Combustion Analysis.Bioresource Technology,1991.37(2): p. 161-168.

The data source of 2 Literature B of table is in (1) Gaspar, A.R., et al., Alternatives for lignocellulosic pulp delignification using polyoxometalates and oxygen:a review.Green Chemistry,2007.9(7):p. 717-730.(2)Seesuriyachan,P.,et al., Improvement in efficiency of lignin degradation by Fenton reaction using synergistic catalytic action.Ecological Engineering,2015.85:p.283-287.(3)Van den Bosch,S.,et al.,Reductive lignocellulose fractionation into soluble lignin-derived phenolic monomers and dimers and processable carbohydrate pulps.Energy Environ.Sci.,2015.(4)Zeng,J., et al.,Biomimetic Fenton-Catalyzed Lignin Depolymerization to High-Value Aromatics and Dicarboxylic Acids.Chemsuschem,2015.8(5):p.861-871.

Embodiment 2: lignin-iron ion Direct Electrolysis hydrogen generating system

Lignin is after cellulose in second biomass resource abundant.However, lignin is recognized always For the material for being low quality and low value.Lignin in pulp and paper industry, only 2% realizes commercial exploitation, is more than 95% is simple directly burning processing, as heat source.There are aromatic structures abundant in lignin, are contained using lignin preparation There is having a high potential for aromatic structure chemicals.Hydrogen content is high in lignin, therefore lignin is also the renewable energy for preparing hydrogen One of source.

(1) mixed solution (the first mixed liquor) is prepared:

In the present embodiment, biomass uses lignin.A certain amount of lignin is added to FeCl₃In aqueous solution, obtain Uniformly mixed mixed solution.

(2) mixed solution is preheated:

Mixed solution is preheated, both contains Fe in the mixed solution obtained after heating²⁺Ion, and contain Fe³⁺, This is called lignin-ferric ion solutions (the second mixed liquor).

(3)Fe³⁺Reducing degree detection

A small amount of lignin-ferric ion solutions are taken to dilute 50,000 times as sample, for analyzing Fe³⁺Reducing degree. Due to Fe²⁺Solution can be transformed into the iron ion complex compound for having extremely strong absorbance in 510nm with the reaction of 1,10- phenanthroline, Fe can be determined by spectrophotometry²⁺Concentration, and then analyze Fe³⁺Reducing degree.

2. electrolysis biological matter hydrogen manufacturing

(1) electrolytic cell is arranged

Biomass electrolytic experiment a laboratory scale, can to carry out in the proton exchange membrane electrolytic cell of continuous operation, As shown in Fig. 1, electrolytic cell is divided into anode electrolysis pond and catholyte pond, and anode electrolysis pond is connected with anode plate, catholyte pond It is connected with cathode plate, anode plate and cathode plate are all made of graphite electrode plate.Proton exchange membrane between two panels graphite electrode plate, Proton exchange membrane cathode lateral load 0.5mg_Ptcm^-2Platinum carbon is as liberation of hydrogen catalyst；Anode plate has multiple runners, and graphite felt is embedding Enter into the runner of anode plate.Cathode is the electrode comprising five layers of gas diffusion paths, and cathode is used uniformly concentration and is The H of 1mol/L₃PO₄Solution is as catholyte.

(2) electrolysis biological matter hydrogen production process

It takes prepared lignin-ferric ion solutions to be placed in anode electrolysis pond respectively, is at the same time 1mol/ by concentration The H of L₃PO₄Aqueous solution is placed in catholyte pond, and two sides under the action of each peristaltic pump, are respectively formed anodic dissolution circulation It is recycled with cathode solution.After both ends liquid circulation is stablized, apply certain outer power-up in the cathode of electrolytic cell and anode two sides Pressure carries out electrolytic hydrogen production, and generated hydrogen is collected in catholyte pond.

3. the electrology characteristic of lignin-ferric ion solutions electrolytic hydrogen production process measures

Several commercial wood elements are used (to select from beauty as raw material, including Kraft cork lignin in the present embodiment The Kraft lignin KL of south paper company, state), alkaline lignin (AL, Sigma-Aldrich) and lignosulfonate (SL, Sigma-Aldrich) respectively with Fe³⁺Form electrolytic hydrogen production system.Iron chloride can be with lignin degrading as oxidized form substance.

3 groups of mixed solutions are prepared respectively, and lignin is respectively KL, AL and SL；Lignin concentration is in each mixed solution 10g/L, FeCl₃Concentration is 1mol/L, is heated to reflux at 100 DEG C, nitrogen protection.Iron ion is main in incipient stage mixed solution It is with Fe³⁺In the presence of, as redox reaction carries out, Fe²⁺Concentration gradually increases.It is determined by ultraviolet-uisible spectrophotometer Fe²⁺Concentration, shown in analysis result such as Fig. 5 (a), in first three hour Fe that reaction starts²⁺Concentration increases sharply, by 28h Reaction, Fe²⁺Final concentration is respectively 0.38,0.42 and 0.37mol/L.

In this experiment, in order to confirm Fe³⁺Effect in lignin electrolytic process selects phosphate aqueous solution, phosphoric acid respectively The parallel laboratory test of aqueous solution and KL lignin as above-mentioned 3 groups of mixed solutions, wherein phosphoric acid is phosphorus in the experiment of anolyte The concentration of acid is 1mol/L, and the mixed solution of phosphoric acid and lignin is 10g/ as lignin concentration in the experiment of anolyte L, phosphoric acid concentration 1mol/L do not contain any Fe in above two groups of experiments³⁺。

By above-mentioned 3 groups of mixed solutions (lignin is respectively KL, AL and SL) Hybrid Heating 6 hours at 100 DEG C respectively, obtain To lignin-ferric ion solutions；50mL anolyte and 80mL catholyte are selected respectively, according in 2 step 2 of embodiment The electrolysis biological matter hydrogen production process of (2) step carries out electrolytic experiment, maintains electrolyte temperature at 90-100 DEG C, while respectively to 2 Group parallel laboratory test selects 50mL anolyte and 80mL catholyte respectively, according to (2) step in 2 step 2 of embodiment Electrolytic hydrogen production process carries out electrolytic experiment, maintains electrolyte temperature at 90 DEG C -100 DEG C or so；Its experimental result such as Fig. 5 (b) institute Show.

As it can be seen that after applying applied voltage, in the circuit of 2 groups of parallel laboratory tests, there is no apparent electric currents to occur, when outer power-up When pressure increases to 1.2V, apparent electric current is not detected yet, it is electrolysis that this explanation, which is worked as with phosphoric acid or phosphoric acid/lignin liquor, When liquid, existing anodic overvoltage during electrolysis water is not reduced.

For 3 groups of lignin-ferric ion solutions, when voltage is increased to 0.7V, it can significantly detect in circuit and deposit In electric current, live current potential (I-V curve bending point) is almost identical；And with the increase of applied voltage, Faradaic current increases Greatly.When additional decomposition voltage is 1.2V, for KL, AL and SL, Faradaic current output valve is respectively 0.341,0.374 He 0.357 A/cm².Three kinds of different lignin variation tendencies are identical, and under identical decomposition voltage, Faradaic current is very close.It is real On border, Fe²⁺Concentration be the key that governing factor in electrolytic process because really anode occur redox reaction electricity Son migration substance is Fe²⁺, Fe²⁺Concentration is higher to mean that decomposition voltage is lower, and electrolysis energy consumption is smaller.Experimental result also indicates that, There is no Fe³⁺Under the conditions of existing, lignin cannot be electrolysed directly as raw material and generate hydrogen, Fe³⁺It is that lignin liquor was electrolysed The catalyst of journey.

(2) influence of the pre-reaction time to electrolytic efficiency

The pre-reaction time of lignin and iron ion is one of the key factor for influencing electrolytic efficiency, and the institute in reaction time It is the Fe in solution because with the extension of reaction time so that hydrogen generation rate can be influenced²⁺Concentration increases, the unit time The amount of charge of interior be transported to anode-side increases caused.

In order to further verify Fe²⁺Correlation between applied voltage, Faradaic current, wood in the mixed solution of use Quality KL concentration is 10g/L, FeCl₃Concentration is 1mol/L, is divided into 5 groups, respectively in 100 DEG C of heating 1h, 6h, 10h, 18h and 28h, nitrogen protection, Fe in obtained lignin-ferric ion solutions²⁺And Fe³⁺Ratio be respectively 0.11,0.30,0.37, 0.51 and 0.62, on the contrary Fe³⁺And Fe²⁺Ratio difference 9.09,3.33,2.70,1.96 and 1.61.Then in other conditions phase Correlation between the decomposition voltage and Faradaic current of mixed solution in the case where after measurement heating.

Shown in experimental result such as Fig. 5 (c), under identical decomposition voltage, preheating time longer lignin KL, i.e. Fe²⁺ Content is higher, and electrolytic current density is bigger.

(3) influence of the lignin concentration to electrolytic hydrogen production

The concentration of biomass is also to influence one of the influence factor of electrolytic hydrogen production efficiency, therefore the present embodiment also tested life Influence of the material concentration for the effect of electrolysis liberation of hydrogen.

FeCl in fixed mixed solution₃Concentration be 1mol/L, be separately added into the powder of KL type lignin, be configured to wooden Plain KL concentration is 4 groups of mixed solutions of 2,10,20 and 30g/L respectively, is heated 6 hours at 100 DEG C, then in other conditions phase Correlation between the decomposition voltage and Faradaic current of mixed solution in the case where after measurement heating.

Shown in experimental result such as Fig. 5 (d).After lignin concentration is more than 10g/L, lignin concentration is further improved, Electrolytic efficiency does not change substantially.

In embodiment 2 in above three part in finally obtained lignin-ferric ion solutions of selected experimental group, pass through Measure Fe³⁺And Fe²⁺Molar ratio in the ratio range of 1:10-10:1；Illustrate to keep Fe³⁺And Fe²⁺Molar ratio in the model In enclosing, stablizing for electrolysis can be kept to carry out.

(4) factor of other influences electrolytic hydrogen production

For liquid catalyst electrolytic hydrogen production system, in test above other than the factor of analyzing influence electrolytic efficiency, also There are two the efficiency that factor influences cathode hydrogen evolution, are the liberation of hydrogen overvoltage of cathode and the faradic efficiency of electrolytic process respectively.

In continuous electrolysis test, apply 100mA/cm²Constant current, and measure H caused by cathode₂Volume.Figure 5 (e) be when Faradaic current is 100mA/cm²When, the decomposition voltage of liberation of hydrogen changes with time process, and effective electrode area is 1cm².As shown in Fig. 5 (e), during electrolytic preparation 24ml hydrogen, decomposition voltage remains stable always.According to faraday Law is it can be calculated that with 100mA/cm²Current density electrolysis process can theoretically prepare 25.89ml H₂.For 1mol/ L FeCl₃- KL, average faradic efficiency are 92.71%, this shows the electronics utilization rate of liquid catalyst electrolytic hydrogen production system very It is high.It is 100mA/cm in current density²When, FeCl₃The power consumption 2.30kWh/Nm of-KL³, with existing literature (Carmo, M., et al.,A comprehensive review on PEM water electrolysis.International Journal Of Hydrogen Energy, 2013.38 (12): the best PEM water electrolysis energy consumption (4.2kWh/ p.4901-4934.) reported Nm³) compare, 45.2% electric energy can be saved by producing same amount of hydrogen.

4. product analysis

As the maximum direct sources of aromatic series/phenolic compound renewable on the earth, using lignin as preparation virtue The raw material of fragrant race's chemicals has great potentiality.However, only very small amount of aromatic compounds is directly from lignin business Upper production, significant challenge first is that natural lignin is a kind of three-dimensional network polymer, depolymerization is at high cost.In liquid catalyst In electrolytic process, electrolysis not only can generate hydrogen from lignin, have much lower energy consumption compared with pure water electrolysis system, And pass through lignin and Fe in entire electrolytic process³⁺Between oxidation reaction by lignin depolymerization be aromatics low molecule quantization Learn substance.Since the world's lignin product for being more than 95% is Kraft lignin (KL lignin), we are in electrolytic experiment The middle primary study degradation process of Kraft lignin.

(1) total organic carbon (TOC) is analyzed

The oxidation of lignin is along with Fe in electrolyte³⁺Reduction process.In this study, catalyst from the state of oxidation to Reducing condition is without regeneration, referred to as oxidation cycle.Then, the Fe of reduction²⁺It is reoxidized under the electric field in anode, and again Raw Fe³⁺It can be recycled in next oxidation cycle.In order to obtain the significant variation of lignin depolymerization, using at 100 DEG C 3 oxidation cycle heating (3 recycle × 6 hours/circulation=18 hours).

After 3 heating-electrolysis cycles, for FeCl₃(1mol/L), the still residual lignin of residue 77.6%. GC the result shows that, in addition to CO₂Outside, there are also a small amount of CH in gas phase₄In the presence of.In water phase, total organic carbon analysis the result shows that, with In FeCl₃In the filtering reacting solution of-KL reaction system, contain 0.90g/L total organic carbon.

According to the weight percent (54.9%) of carbon content in former pine lignin, go out 3 times from TOC Analysis result calculation FeCl₃The amount of lignin oxidation's product in aqueous solution is dissolved after reaction cycle.Solid residue, liquid, gas etc. part with FeCl₃Organic carbon content is as shown in Figure 6 after reaction, it is seen that than using PMo₁₂(concentration 0.1mol/L, heat 6h) effect is more It is good.

In addition, improving the conversion degree that reaction temperature will also improve lignin.For example, when reaction temperature rise to it is 190 DEG C 1 small When, 26.6% solid lignin is oxidized to low-molecular weight water-soluble lignin segment, and it is small that this is apparently higher than at 100 DEG C 18 When 14.0% degradation rate.This illustrates that raising reaction temperature can be with significantly accelerated lignin and Fe³⁺Between oxidizing reaction rate, Improve the palliating degradation degree of lignin.

(2) GC-mass is analyzed

Pass through 30ml ether (C₂H₅)₂O extracts the oxidation product of lignin from 50ml reaction solution, then passes through GC-MS (Agilent 450-GC Bruker Varian 300-MS) is analyzed.As shown in fig. 7, Fig. 7 is lignin KL and FeCl₃ After cell reaction, analysis acquired results, reaction condition are carried out to product liquid using GC-Mass are as follows: KL (10g/L), FeCl₃ (1mol/L), 100 DEG C, 18h nitrogen protection preheating, analysis result is to have vanillic aldehyde in solution, 4- tolyl aldehyde, benzoic acid, The chemicals that phthalic anhydride and other chlorine replace.

Claims

1. a kind of method of Direct Electrolysis biomass hydrogen preparation, which is characterized in that using oxidation-reduction pair as electrolysis biological matter Catalyst and electron transit mediator in hydrogen production process；

The electrolysis biological matter hydrogen production process carries out in proton exchange membrane electrolysis cells, the chemical reaction in biomass electrolytic process Equation are as follows:

In anode reaction pond:

In anode-side:

Reduced form substance-e^-→ oxidized form substance (2)

In cathode side:

Net chemical reaction are as follows:

Biomass+H₂O → biomass oxidation product+CO₂+H₂ (4)

In anode reaction pond, the first mixed liquor containing biomass and oxidized form substance is preheated, when oxidized form substance is When inorganic elements, preheating temperature is 25-250 DEG C, and when oxidized form substance is organic element, preheating temperature is 25-150 DEG C；In advance After thermal response, the second mixed liquor is obtained；Contain oxidation-reduction pair in second mixed liquor, wherein oxidized form substance and also The molar ratio of prototype substance is 1:10-10:1；In the electrolytic process, the temperature of anolyte and catholyte is controlled System is at 50-100 DEG C；

The oxidation-reduction pair selects Fe³⁺/Fe²⁺、Ag⁺/Ag、Mn⁴⁺/Mn²⁺、TEMPO⁺/TEMPO、AQ⁺One of/AQ；

The biomass be glucose, potato starch, lignin, cellulose, hemicellulose, stalk, vinasse, algae, seaweed, One of sludge organic matter is a variety of.

2. the method for Direct Electrolysis biomass hydrogen preparation according to claim 1, which is characterized in that first mixed liquor In, the concentration of oxidized form substance is 0.1-5mol/L；When biomass is soluble biomass, biomass concentration 0.1- 4mol/L；When biomass is insoluble or less soluble biomass, biomass concentration 1-30g/L.

3. a kind of system using the method according to claim 1 Direct Electrolysis biomass hydrogen preparation, feature exist In, including electrolytic cell and electrode, electrolytic cell be divided into anode electrolysis pond and catholyte pond by proton exchange membrane；Containing biomass and oxygen After the preheated reaction of the first mixed liquor of change type substance, the second mixed liquor containing oxidation-reduction pair is obtained, as anode electricity Solve liquid；

Chemical equation in biomass electrolytic process are as follows:

In anode reaction pond:

In anode-side:

Reduced form substance-e^-→ oxidized form substance (2)

In cathode side:

Net chemical reaction are as follows:

Biomass+H₂O → biomass oxidation product+CO₂+H₂ (4)。

4. the system of Direct Electrolysis biomass hydrogen preparation according to claim 3, which is characterized in that the oxidized form substance is Fe³⁺、Ag⁺、Mn⁴⁺、TEMPO⁺、AQ⁺One of, obtained oxidation-reduction pair is respectively Fe³⁺/Fe²⁺, Ag⁺/ Ag, Mn⁴⁺/Mn² ⁺, TEMPO⁺/ TEMPO, AQ⁺/AQ。

5. the system of Direct Electrolysis biomass hydrogen preparation according to claim 3, which is characterized in that anode plate can have one Or multiple runners, cathode plate may include multi-layer gas diffusion admittance.

6. the system of Direct Electrolysis biomass hydrogen preparation according to claim 3, which is characterized in that the cathode of proton exchange membrane One of lateral load noble metal catalyst, non-precious metal catalyst and non-metallic catalyst are a variety of.

7. a kind of oxidation-reduction pair is in the method according to claim 1 and such as any one of claim 3-6 Application in the system, which is characterized in that using the oxidation-reduction pair as catalyst and electron transit mediator, for straight Connect electrolysis biological matter hydrogen manufacturing；

In anode reaction pond:

In anode-side:

Reduced form substance-e^-→ oxidized form substance (2)

In cathode side:

Net chemical reaction are as follows:

Biomass+H₂O → biomass oxidation product+CO₂+H₂ (4)。