# Patent

## Title
Hydrogen sulfide scavenger

## Abstract

The present disclosure is related to a family of metals chelates for use as a hydrogen sulfide scavenger in asphalt, and the preparation thereof. The metal chelates, in particular amino acid metal chelates, are particularly efficient at reducing the hydrogen sulfide emissions of asphalt.

## Background
FIELD OF THE INVENTION
The present disclosure relates to a hydrogen sulfide scavenger for use as an additive in asphalt.
BACKGROUND OF THE INVENTION
Asphalt is commonly used in the construction and paving of roads. Asphalt is a mixture of aggregate material, such as sand, gravel, and crushed stone, with hot bitumen. The bitumen coats the aggregate material to give the asphalt, which may be spread as a uniform layer upon a road bed and compacted and smoothed with heavy rolling equipment.
Asphalt invariably contains sulfur. The amount of sulfur will depend on the origin of the crude oil, as well as the processes used to refine the crude oil, into asphalt. The sulfur may exist in different forms. For example, sulfur may be in the form of hydrogen sulfide. Hydrogen sulfide, or dihydrogen sulfide, is a chemical compound with the formula H2S. It is a colorless, poisonous, flammable gas with the characteristic foul odor.
Hydrogen sulfide may be released form asphalt, in particular when the asphalt is heated to a certain temperature. For example, hydrogen sulfide results from the dehydrogenation reactions that occur between bitumen and sulfur at the hot mixing temperatures, e.g. temperatures greater than 140° C. Hydrogen sulfide emissions are regulated. Therefore, there exists a need to reduce the amount of hydrogen sulfide in asphalt. Accordingly, the present disclosure provides for a reduced or low release of hydrogen sulfide during the preparation of asphalt, as well as in the final asphalt material.
SUMMARY OF THE INVENTION
The present disclosure is related to a family of metals chelates for use as a hydrogen sulfide scavenger in asphalt, and the preparation thereof. The metal chelates, in particular amino acid metal chelates, are particularly efficient at reducing the hydrogen sulfide emissions of asphalt.
The present disclosure is directed to a composition comprising asphalt and an amino acid metal chelate. In some embodiments, the amino acid metal chelate is selected from the group consisting of copper bis-glycinate, zinc bis-glycinate and mixtures thereof.
The present disclosure is also directed to a method of reducing hydrogen sulfide emission from asphalt, or the preparation thereof, comprising the step of combining an amino acid metal chelate to asphalt, or an asphalt mix. In some embodiments, the amino acid metal chelate is selected from the group consisting of copper bis-glycinate, zinc bis-glycinate and mixtures thereof.
The amino acid metal chelate may also be selected form the following: Boron Amino Acid Chelate; Boron Aspartate; Boron Citrate; Boron Glycinate; Calcium Alphaketoglutarate; Calcium Amino Acid Chelate; Calcium Arginate; Calcium Ascorbate; Calcium Aspartate; Calcium Caprylate; Calcium Carbonate; Calcium Citrate Malate; Calcium Glycinate; Calcium D-Glucarate; Calcium Krebs Cycle; Calcium Lactate; Calcium Malate; Calcium Orotate; Calcium Succinate; Chromium Amino Acid Chelate; Chromium Arginate; Chromium Chloride; Chromium Dinicotinate/Glycinate; Chromium Picolinate; Chromium Nicotinate; Chromium Trit; Chromium Yeast; Chromium Nicotinate/Glycinate; Copper Amino Acid Chelate; Copper Aspartate; Copper Carbonate; Copper Citrate; Copper Gluconate; Copper Glycinate; Copper Sulfate; Copper Yeast; Iron Amino Acid Chelate; Iron Aspartate; Iron Bis-Glycinate HCl Soluble; Iron Citrate; Iron Fumarate; Iron Gluconate; Iron Glycinate; Iron Sulfate; Iron Yeast; Lithium Aspartate; Lithium Orotate; Magnesium Alphaketoglutarate; Magnesium Amino Acid Chelate; Magnesium Ascorbate; Magnesium Aspartate; Magnesium Citrate; Magnesium Gluconate; Magnesium Glycinate; Magnesium Malate; Magnesium Orotate; Magnesium Oxide; Magnesium Succinate; Magnesium Taurinate; Magnesium Yeast; Manganese Amino Acid Chelate; Manganese Aspartate; Manganese Carbonate; Manganese Citrate; Manganese Gluconate; Mananese Glycinate; Manganese Sulfate; Manganese Yeast; Molybdenum Amino Acid Chelate; Molybdenum Trit; Molybdenum Yeast; Sodium Molybdate; Phosphorus Amino Acid Chelate; Dicalcium Phosphate; Potassium Amino Acid Chelate; Potassium Ascorbate; Potassium Aspartate; Potassium Citrate; Potassium Chloride; Potassium D-Glucarate; Potassium Gluconate; Potassium Glycerophosphate; Potassium Iodide Trit; Potassium Succinate; Selenium Amino Acid Chelate; Selenium Aspartate; L-Selenomethionine; Selenium Yeast; Sodium Selenate; Sodium Selenite; Strontium Aspartate; Strontium Citrate; Strontium Glycinate; Vanadium Amino Acid Chelate; Vanadium Citrate; Bis-Maltolato Oxo Vanadium; Vanadyl Sulfate; Sodium Metavanadate; Zinc Acetate; Zinc Arginate; Zinc Amino Acid Chelate; Zinc Ascorbate; Zinc Aspartate; Zinc Gluconate; Zinc Glycinate; Zinc Methionate; Zinc Oxide; Zinc Picolinate; Zinc Sulfate; and Zinc Yeast


EXAMPLES
Example 1
Hydrogen sulfide emissions were measured from asphalt samples containing an amino acid metal chelate versus a control containing no amino acid metal chelate. Three asphalt samples were prepared and their hydrogen sulfide emissions measured after 1 hour in storage. To two samples, 0.5% amino acid metal chelate additive was added, CuGlyc (copper bis-glycinate) and ZnGlyc (zinc bis-glycinate) respectively. The hydrogen sulfide emissions were measured again after 5 minutes and 1 hour. Table 1 lists the results. The addition of the amino acid metal chelate showed significant reduction in hydrogen sulfide emissions.







TABLE 1







Hydrogen Sulfide Emission
















H2S (ppm)
H2S (ppm)





H2S (ppm)
5 minutes
1 hour after





Storage
after
adding





at 160,
addition of
scavenger


% Additive

Temp
one hour
scavenger
material















0
Control
180° C.
16

10


0.5
CuGlyc
180° C.
12
4
1


0.5
ZnGlyc
180° C.
10
5
1









Example 2
Additional amino acid metal chelates that may be used in asphalt, or the preparation thereof, are listed in Table 2.







TABLE 2







Amino Acid Metal Chelates










Metal
Chelating agent






Chromium
Amino Acid




Arginate Chloride




Dinicotinate/Glycinate




Picolinate




Nicotinate




TritChromium Yeast



Copper
Amino Acid




Aspartate




Carbonate




Citrate




Gluconate




Sulfate




Yeast



Iron
Amino Acid




Aspartate




Bis-Glycinate




Citrate




Fumarate




Gluconate




Sulfate




Yeast



Manganese
Amino Acid




Aspartate




Carbonate




Citrate




Gluconate




Sulfate




Yeast



Molybdenum
Amino Acid




TritMolybdenum




Yeast




Sodium Molybdate



Selenium
Amino Acid




Aspartate




L-Selenomethionine




Yeast




Sodium Selenate




Sodium Selenite



Strontium
Aspartate




Citrate




Glycinate



Vanadium
Amino Acid




Citrate




Bis-Maltolato Oxo Vanadium




Vanadyl Sulfate




Sodium Metavanadate



Zinc
Acetate




Arginate




Amino Acid




Ascorbate




Aspartate




Gluconate




Glycinate




Methionate




Picolinate




Sulfate




Yeast

## Claims

1. A composition comprising:
(i) asphalt or an asphalt mix, and
(ii) an amino acid metal chelate, wherein the amino acid metal chelate is selected from the group consisting of copper bis-glycinate and zinc bis-glycinate.

2. A method of reducing hydrogen sulfide emission from asphalt or from the preparation of asphalt, comprising the step of:
(i) combining an amino acid metal chelate to as or asphalt mix, wherein the amino add metal chelate is selected from the group consisting of copper bis-glycinate and zinc bis-glycinate.