LU500323B1

LU500323B1 - Method for measuring and calculating content of sulfuric acid catalyst in furfural residue

Info

Publication number: LU500323B1
Application number: LU500323A
Authority: LU
Inventors: Chuyi Xiong; Yiming Yu; Jun Wang; Bingquan Hua; Qianqian Yuan; Zhen Xu; Hongjuan Li; Mingqiang Chen; Jun Wan; Yanru Zhao
Original assignee: Univ Anhui Sci & Technology
Priority date: 2021-03-12
Filing date: 2021-06-24
Publication date: 2022-01-07
Also published as: CN113049431A

Abstract

The present invention discloses a method for measuring and calculating the content of sulfuric acid catalyst in furfural residue, including the following steps: S1: repeatedly washing furfural residue, S2: performing a precipitation reaction on the furfural residue filtrate, S3: calculating the total sulfuric acid content in a furfural residue sample, and S4: measuring and calculating the recovery rate of the sulfuric acid recovered in the washing liquid. The measuring and calculating method of the present invention has no need of expensive high-end instruments in the measuring and calculating process, but only requires conventional cheap instruments, equipment, and materials such as balances, ovens, funnels, and filter paper. The measuring and calculating method of the present invention has high measuring and calculating accuracy and a relative error range of ±4.6%. The measuring and calculating method has the advantages of simple operation, low operation cost and short analysis period, and is particularly suitable for small and medium-sized enterprises and laboratories lacking high-end instruments and equipment.

Description

METHOD FOR MEASURING AND CALCULATING CONTENT OF SULFURIC ACID CATALYST IN FURFURAL RESIDUE

BACKGROUND Technical Field The present invention relates to a measuring and calculating method, and in particular relates to a method for measuring and calculating content of sulfuric acid catalyst in furfural residue. Related Art Furfural is an important fine chemical product with a wide range of uses. Furfural is currently mainly produced by catalyzing the hydrolysis of corn cobs and other biomass with sulfuric acid as a catalyst. Finally, sulfuric acid is present in the solid residue (commonly known as furfural residue) after furfural is extracted. In the industry, the furfural residue is generally used as boiler fuel. During the combustion process, sulfuric acid is decomposed into sulfur trioxide and discharged from a furnace along with the flue gas. If the flue gas is not desulfurized and purified, the sulfur trioxide will cause air pollution. Washing the furfural residue with water can dissolve part of the sulfuric acid in the water. Then, through solid-liquid separation, filtrate containing sulfuric acid can be used to catalyze the hydrolysis of biomass to produce furfural after being concentrated or supplemented with part of sulfuric acid catalyst. The content of sulfuric acid in a filter cake is greatly reduced and the filter cake can be used to make organic fertilizer. In the process of recovering and reusing sulfuric acid in the furfural residue and resource utilization of the furfural residue, it is necessary to know the content of sulfuric acid in the water washing filtrate of the furfural residue, the content of sulfuric acid in the original furfural residue, and the content of residual sulfuric acid in the furfural residue after water washing. At the same time, only when the content is confirmed can the recovery rate of sulfuric acid in the process of treating the furfural residue by the water washing method be further calculated. Therefore, there is an urgent need for a method for measuring and calculating the recovery rate of sulfuric acid catalyst in furfural residue.

SUMMARY The objective of the present invention is to provide a method for measuring and calculating content of sulfuric acid catalyst in furfural residue. The measuring and calculating process has no need of expensive high-end instruments, only balances, ovens, funnels, filter paper and other conventional cheap instruments, equipment and materials are required.

The method of the present invention has high measuring and calculating accuracy, and the relative error range is +4.6%. The measuring and calculating method of the present invention has the advantages of simple operation, low operation cost, and short analysis period, and is particularly suitable for small and medium-sized enterprises and laboratories lacking high-end instruments and equipment.

The objective of the present invention can be achieved by the following technical solution: A method for measuring and calculating the content of sulfuric acid catalyst in furfural residue includes the following steps: S1: repeatedly washing furfural residue, S2: performing a precipitation reaction on the furfural residue filtrate, S3: calculating the total sulfuric acid content in a furfural residue sample, and S4: measuring and calculating the recovery rate of the sulfuric acid recovered in the washing liquid.

Further, the liquid used for washing the furfural residue in S1 is deionized water at a temperature of 10°C-100°C, and the mass ratio of the deionized water to the furfural residue is 4:1-5:1. Washing is fully performed each time and then filtration is performed until the pH value of the liquid is constant.

The filter cake is washed again and repeatedly until the pH value of the filtrate reaches 7, and finally all the washing filtrates are mixed.

Further, the precipitating agent used in S2 is an aqueous solution of barium chloride at a concentration of 0.1-0.5 mol/L, and the reaction formula is: H,SO, + BaCL, — BaSO, + +2HCL After the precipitation is completed, filtration is performed with three layers of quantitative filter paper, and the obtained precipitate is heated at a temperature of 300-500°C for 1 hour or above until the weight of the precipitate no longer changes.

Further, the total sulfuric acid content in the furfural residue sample in S3 is calculated as: H,SO,% = 0.41988 x 2 x100% , where W, is the weight of the furfural residue 1 sample, W, is the weight of the precipitated barium sulfate, and 0.41988 is the conversion coefficient.

Further, the calculation formula of the recovery rate of sulfuric acid recovered in the washing liquid in S4 is: R = <x 100% , where À is the weight of sulfuric acid recovered inthe filtrate, and 47 is the total weight of sulfuric acid contained in the furfural residue.

The present invention has the following beneficial effects:

1. The measuring and calculating method of the present invention has no need of expensive high-end instruments in the measuring and calculating process, but only requires conventional cheap instruments, equipment, and materials such as balances, ovens, funnels, and filter paper.

2. The measuring and calculating method of the present invention has high measuring and calculating accuracy and a relative error range of +4.6%. The measuring and calculating method has the advantages of simple operation, low operation cost and short analysis period, and is particularly suitable for small and medium-sized enterprises and laboratories lacking high-end instruments and equipment.

DETAILED DESCRIPTION The technical solutions in the examples of the present invention are clearly and completely described below. It is obvious that the described examples are only part of the examples of the present invention, and not all the examples. All other examples obtained by a person of ordinary skill in the art based on the examples of the present invention without creative efforts shall fall within the protection scope of the present invention.

A method for measuring and calculating the recovery rate of sulfuric acid catalyst in furfural residue includes the following steps: S1: furfural residue 1s repeatedly washed À certain amount of dried furfural residue is taken and the weight is denoted as W, (g). Sufficient washing water at a temperature of 10°C-100°C (preferably 60°C-90°C) is added to mix with the furfural residue. The washing water is deionized water. The mass ratio of the washing water to the furfural residue (liquid-solid ratio for short) is 4:1-5:1 to obtain a suspension of the furfural residue, which is referred to as a first suspension. The first suspension is fully stirred and washed, and the PH value of the aqueous solution in the suspension is monitored at the same time. When the 7 H value of the aqueous solution is constant, the stirring and washing are stopped. The suspension is filtered to achieve solid-liquid separation to obtain a first filtrate and a first filter cake. The first filtrate is reserved.

The PH value of the first filtrate is measured. If the P77 value of the filtrate is less than 7, it indicates that the first filter cake still contains sulfuric acid. A certain amount of deionized water is added to the first filter cake and mixed to form a new furfural residue suspension, referred to as the second suspension. The second suspension is fully stirred and washed, and the 7 H value of the aqueous solution in the second suspension is monitored at the same time. When the 7 value of the aqueous solution is constant, stirring and washing are stopped, and the second suspension is filtered to obtain a second filtrate and a second filter cake. The PH value of the second filtrate is measured. If the PX value is still less than 7, the second filter cake is continued to be washed with deionized water. The furfural residue is washed repeatedly in such a way until the / H value of a N th filtrate obtained from the N th washing is equal to 7, then washing is stopped. The mass (8) of each filtrate is denoted as T1, Mi ™¥ in turn. All the filtrates are mixed and supplied to the next operation.

S2: Precipitation reaction is performed on furfural residue filtrate A sufficient barium chloride aqueous solution is added to the filtrate obtained in the first step, where the concentration of the barium chloride is 0.1-0.5 mol/L, so that all sulfate ions in the filtrate are precipitated as barium sulfate. The reaction formula is as follows: H,SO, + BaCL, > BaSO, + +2HCL 1) The suspension of the barium chloride precipitate is filtered to obtain the barium chloride precipitate. Since the barium sulfate precipitate is very small, three layers of quantitative filter paper are required for filtration to prevent the precipitate from penetrating the filter paper and entering the filtrate. A small amount of clear filtrate is added into a beaker, and a drop of barium chloride aqueous solution is added. If the filtrate becomes turbid again, it means that the precipitation of the filtrate is incomplete, and the barium chloride solution needs to be added to the clear filtrate again for precipitation reaction, and then the suspension is filtered. When the barium chloride solution is added dropwise to the clear filtrate and the filtrate no longer becomes turbid, it indicates that the sulfate radicals in the filtrate are completely precipitated.

All the obtained precipitate is heated at a temperature of 300-500°C for 1 hour or above until the weight of the precipitate no longer changes. The obtained dry precipitate is weighed and the weight is denoted as W, (g), S3: total sulfuric acid content in furfural residue sample is calculated The total absolute content is denoted as Wiis, (g), and calculated as follows: Wii so, = x 98 BaSO, (2)

where W2 is the weight of the barium sulfate precipitate, M aso, is the molar mass of barium sulfate, which is equal to 233.4 g/mol, and the molar mass of sulfuric acid is 98 g/mol, which is substituted into formula (2) to obtain: WW, so, = 0.41988 x W, 3) 5 Total relative content of sulfuric acid in a furfural residue sample 7250:% 0 W, H,SO,% =0.41988 x — x 100% 7 (4) S4: the recovery rate of sulfuric acid recovered in washing liquid is measured and calculated The total percentage of sulfuric acid contained in the furfural residue is measured and calculated in S1 to S3, and only a small amount of furfural residue sample needs to be weighed for analysis to complete the determination.

When a large amount of furfural residue is washed to recover sulfuric acid for reuse, economically, it is impossible to recover all the sulfuric acid from furfural into the filtrate, because the process not only requires a large amount of water but also takes a long time.

Generally, the mass ratio of washing water to furfural residue (liquid-solid ratio) is 4:1-5:1, and most of the sulfuric acid (75%-85%) in furfural residue can be recovered by washing twice.

Assuming that the actually washed furfural residue is 4 Æ8 (dry basis), the filtrate A, Kg is obtained after washing and filtration, a small amount of sample ® B is taken from the filtrate A, the precipitation reaction is performed on the % S sample according to the second step to obtain the dried barium sulfate precipitate, denoted as 42 B, Wr; in the formula (3) is replaced with 32, which is multiplied with the conversion factor “2/1, and the absolute amount ~~ (7%) of the recovered sulfuric acid in the filtrate 4, is: A=0.41988x 4, xa, /a, (5) The total sulfuric acid content in A Kg furfural residue is measured and calculated according to the method of the first step to the third step.

The total relative content of 24e . . H.S0.% sulfuric acid in the sample is calculated by formula (4) and is denoted by “274 "°, then the total sulfuric acid content AT (Kg) in 4 Kg furfural residue is as follows: AT = A, x H,50,% (6)

The recovery rate À of sulfuric acid recovered into the washing liquid is calculated as follows: R= 100% AT (7) Example 1 A dried furfural residue No. 1 sample was taken. The weight was denoted as Wi (2), the weight is W.=10.0160 g, and the relative content of sulfuric acid in the No. 1 sample is

5.982%. 50 g of deionized water at a temperature of 90°C was added and mixed to obtain a first suspension. The first suspension was fully stirred and washed. At the same time, the pH value of the aqueous solution in the suspension was monitored. When the / H value of the aqueous solution is constant, stirring and washing were stopped. The suspension was filtered to achieve solid-liquid separation to obtain a first filtrate and a first filter cake.

Deionized water was added to the first filter cake and mixed to form a new furfural residue suspension. The above operation was repeated 5 times, 250 g of deionized water was consumed, and suction filtration was performed to obtain a total of 170.5 g of filtrate. The filtrate was subjected to a full precipitation reaction according to the operation of S2, and finally the obtained dried barium sulfate precipitate Wr, =1 4812 g. The value was substituted into formula (4) to obtain the total relative content of the sulfuric acid #.50.% =6.209% in the sample. The relative deviation between the determined value and the actual content is 3.794%.

Another 10 Kg of furfural residue No. 1 was sampled, and 50 Kg of hot water at 90°C was added and fully stirred, mixed, and washed for 0.5 hour. Then the suspension was subjected to press filtration to obtain a recovered first filtrate 29.6 Kg . 50 Kg of hot water at 90°C was added to the filter cake obtained after press filtration, and fully stirred, mixed, and washed for 0.5 hour. Then the obtained suspension was subjected to press filtration to obtain a recovered second filtrate 49.2 Kg The recovered two filtrates were mixed to a total of 788 #8 10 8 of the mixed filtrate was taken for performing the precipitation reaction according to the method described in the second step to obtain dried barium sulfate precipitate %=0.1501 g. According to formulas (5)-(7), the actual recovery rate of sulfuric acid is calculated as 79.59%.

Example 2

A dried furfural residue No. 2 sample was taken. The weight was denoted as Wi (g), the weight is W.=10.0121 g, and the relative content of sulfuric acid in the No. 2 sample 1s

2.883%. 50 g of deionized water at a temperature of 90°C was added and mixed to obtain a first suspension. The first suspension was fully stirred and washed. At the same time, the value of the aqueous solution in the suspension was monitored. When the value of the aqueous solution is constant, stirring and washing were stopped. The suspension was filtered to achieve solid-liquid separation to obtain a first filtrate and a first filter cake. Deionized water was added to the first filter cake and mixed to form a new furfural residue suspension. The above operation was repeated 10 times, 250 g of deionized water was consumed, and suction filtration was performed to obtain a total of 170.5 g of filtrate. The filtrate was subjected to a full precipitation reaction according to the operation of S2, and finally the obtained dried barium sulfate precipitate W=1 4812 g. The value was substituted into formula (4) to obtain the total relative content of the sulfuric acid #.50.% =2.7528% in the sample. The relative deviation between the determined value and the actual content is 4.5160%. Kg ; Kg Another 10 of furfural residue No. 2 was sampled, and 50 of hot water at 90°C was added and fully stirred, mixed, and washed for 0.5 hour. Then the suspension was subjected to press filtration to obtain a recovered first filtrate 29.6 Kg . 50 Kg of hot water at 90°C was added to the filter cake obtained after press filtration, and fully stirred, mixed, and washed for 0.5 hour. Then the obtained suspension was subjected to press filtration to obtain a recovered second filtrate 49.2 KZ. The recovered two filtrates were mixed to a total of 78.8 #8 10 8 of the mixed filtrate was taken for performing the precipitation reaction according to the method described in the second step to obtain dried barium sulfate precipitate %=0.1501 g. According to formulas (5)-(7), the actual recovery rate of sulfuric acid is calculated as 75.18%. Example 3 A dried furfural residue No. 3 sample was taken. The weight was denoted as Wi (g), the weight is W,=9.01252 g, and the relative content of sulfuric acid in the No. 3 sample 1s

8.673%. 50 g of deionized water at a temperature of 90°C was added and mixed to obtain a first suspension. The first suspension was fully stirred and washed. At the same time, the pH value of the aqueous solution in the suspension was monitored. When the / H value of the aqueous solution is constant, stirring and washing were stopped. The suspension was filtered to achieve solid-liquid separation to obtain a first filtrate and a first filter cake.

Deionized water was added to the first filter cake and mixed to form a new furfural residue suspension. The above operation was repeated 15 times, 250 g of deionized water was consumed, and suction filtration was performed to obtain a total of 170.5 g of filtrate.

The filtrate was subjected to a full precipitation reaction according to the operation of S2, and finally the obtained dried barium sulfate precipitate W=1 4812 g. The value was substituted into formula (4) to obtain the total relative content of the sulfuric acid #.50.% =8.792% in the sample. The relative deviation between the determined value and the actual content is 1.372%.

Another 10 ÉS of furfural residue No. 3 was sampled, and 50 K8 of hot water at 90°C was added and fully stirred, mixed, and washed for 0.5 hour. Then the suspension was subjected to press filtration to obtain a recovered first filtrate 29.6 Kg . 50 Kg of hot water at 90°C was added to the filter cake obtained after press filtration, and fully stirred, mixed, and washed for 0.5 hour. Then the obtained suspension was subjected to press filtration to obtain a recovered second filtrate 49.2 Kg The recovered two filtrates were mixed to a total of 78.8 #8 10 8 of the mixed filtrate was taken for performing the precipitation reaction according to the method described in the second step to obtain dried barium sulfate precipitate 32=0.1501 g. According to formulas (5)-(7), the actual recovery rate of sulfuric acid is calculated as 83.56%.

In the descriptions of this specification, a description of a reference term such as "an embodiment", "an example", or "a specific example" means that a specific feature, structure, material, or characteristic that is described with reference to the embodiment or the example is included in at least one embodiment or example of the present invention. In this specification, exemplary descriptions of the foregoing terms do not necessarily refer to the same embodiment or example. In addition, the described specific features, structures, materials, or characteristics may be combined in a proper manner in any one or more of the embodiments or examples.

The foregoing displays and describes basic principles, main features of the present invention and advantages of the present invention. A person skilled in the art may understand that the present invention is not limited to the foregoing examples. Descriptions in the examples and this specification only illustrate the principles of the present invention.

Various modifications and improvements are made in the present invention without departing from the spirit and the scope of the present invention, and these modifications and improvements shall fall within the protection scope of the present invention.

Claims

CLAIMS What is claimed is:

1. A method for measuring and calculating content of a sulfuric acid catalyst in furfural residue, comprising the following steps: S1: repeatedly washing furfural residue, S2: performing a precipitation reaction on the furfural residue filtrate, S3: calculating the total sulfuric acid content in a furfural residue sample, and S4: measuring and calculating the recovery rate of the sulfuric acid recovered in the washing liquid.

2. The measuring and calculating method of claim 1, wherein the liquid used for washing the furfural residue in S1 is deionized water at a temperature of 10°C-100°C, and the mass ratio of the deionized water to the furfural residue is 4:1-5:1; washing is fully performed each time and then filtration is performed until the pH value of the liquid is constant; the filter cake is washed again and washed repeatedly until the 7 H value of the filtrate reaches 7; and finally all the washing filtrates are mixed.

3. The measuring and calculating method of claim 1, wherein the precipitating agent used in S2 is an aqueous solution of barium chloride at a concentration of 0.1-0.5 mol/L, and the reaction formula is: H,SO, + BaCL, — BaSO, + +2HCL after the precipitation is completed, filtration is performed with three layers of quantitative filter paper, and the obtained precipitate is heated at a temperature of 300-500°C for 1 hour or above until the weight of the precipitate no longer changes.

4. The measuring and calculating method of claim 1, wherein the total sulfuric acid content in the furfural residue sample in 5S3 is calculated as: H,SO,% = 0.41988 12 100% W , where Wi is the weight of the furfural residue sample, W2 is the weight of the precipitated barium sulfate, and 0.41988 is the conversion coefficient.

5. The measuring and calculating method of claim 1, wherein the calculation formula of R= A x 100% the recovery rate of sulfuric acid recovered in the washing liquid in S4 is: AT , where À is the weight of sulfuric acid recovered in the filtrate, and 47" is the total weight of sulfuric acid contained in the furfural residue.